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Cypress Hill

Cypress Hill is an American hip hop group from South Gate, California, formed in 1988. They have sold over 20 million albums worldwide, and they have obtained multi-platinum and platinum certifications. The group has been critically acclaimed for their first five albums. They are considered to be among the main progenitors of West Coast hip hop and 1990s hip hop. All of the group members advocate for medical and recreational use of cannabis in the United States. In 2019, Cypress Hill became the first hip hop group to have a star on the Hollywood Walk of Fame.

Formation (1988)
Senen Reyes (also known as Sen Dog) and Ulpiano Sergio Reyes (also known as Mellow Man Ace) are brothers born in Pinar del Río, Cuba. In 1971, their family immigrated to the United States and initially lived in South Gate, California. In 1988, the two brothers teamed up with New York City native Lawrence Muggerud (also known as DJ Muggs, previously in a rap group named 7A3) and Louis Freese (also known as B-Real) to form a hip-hop group named DVX (Devastating Vocal Excellence). The band soon lost Mellow Man Ace to a solo career, and changed their name to Cypress Hill, after a street in South Gate.

Mainstream success with Cypress Hill and Black Sunday, addition of Eric Bobo, and III: Temples of Boom (1989–1996)
After recording a demo in 1989, Cypress Hill signed a record deal with Ruffhouse Records. Their self-titled first album was released in August 1991. The lead single was the double A-side "The Phuncky Feel One"/"How I Could Just Kill a Man" which received heavy airplay on urban and college radio, most notably peaking at No. 1 on Billboard Hot Rap Tracks chart and at No. 77 on the Billboard Hot 100. The other two singles released from the album were "Hand on the Pump" and "Latin Lingo", the latter of which combined English and Spanish lyrics, a trait that was continued throughout their career. The success of these singles led Cypress Hill to sell two million copies in the U.S. alone, and it peaked at No. 31 on the Billboard 200 and was certified double platinum by the RIAA. In 1992, Cypress Hill's first contribution to a soundtrack was the song "Shoot 'Em Up" for the film Juice. The group made their first appearance at Lollapalooza on the side stage in 1992. It was the festival's second year of touring, and featured a diverse lineup of acts such as Red Hot Chili Peppers, Ice Cube, Lush, Tool, Stone Temple Pilots, among others. The trio also supported the Cypress Hill album by touring with the Beastie Boys, who were touring behind their third album Check Your Head.

Black Sunday, the group's second album, debuted at No. 1 on the Billboard 200 in 1993, recording the highest Soundscan for a rap group up until that time. "Insane in the Brain" became a crossover hit, peaking at No. 19 on the Billboard Hot 100, at No. 16 on the Dance Club Songs chart, and at No. 1 on the Hot Rap Tracks chart. "Insane in the Brain" also garnered the group their first Grammy nomination. Black Sunday went triple platinum in the U.S. and sold about 3.26 million copies. Cypress Hill headlined the Soul Assassins tour with House of Pain and Funkdoobiest as support, then performed on a college tour with Rage Against the Machine and Seven Year Bitch. Also in 1993, Cypress Hill had two tracks on the Judgment Night soundtrack, teaming up with Pearl Jam (without vocalist Eddie Vedder) on the track "Real Thing" and Sonic Youth on "I Love You Mary Jane". The soundtrack was notable for intentionally creating collaborations between the rap/hip-hop and rock/metal genres, and as a result the soundtrack peaked at No. 17 on the Billboard 200 and was certified gold by the RIAA. On October 2, 1993, Cypress Hill performed on the comedy show Saturday Night Live, broadcast by NBC. Prior to their performances, studio executives, label representatives, and the group's own associates constantly asked the trio to not smoke marijuana on-stage. DJ Muggs became irritated due to the constant inquisitions, and he subsequently lit a joint during the group's second song. Up until that point, it was extremely uncommon to see marijuana usage on a live televised broadcast. The incident prompted NBC to ban the group from returning on the show, a distinction shared only by six other artists.

The group later played at Woodstock 94, officially making percussionist Eric Bobo a member of the group during the performance. Eric Bobo was known as the son of Willie Bobo and as a touring member of the Beastie Boys, who Cypress Hill previously toured with in 1992. That same year, Rolling Stone named the group as the Best Rap Group in their music awards voted by critics and readers. Cypress Hill then played at Lollapalooza for two successive years, topping the bill in 1995. They also appeared on the "Homerpalooza" episode of The Simpsons. The group received their second Grammy nomination in 1995 for "I Ain't Goin' Out Like That".

Cypress Hill's third album III: Temples of Boom was released in 1995, peaking at No. 3 on the Billboard 200 and at No. 3 on the Canadian Albums Chart. The album was certified platinum by the RIAA. "Throw Your Set in the Air" was the most successful single off the album, peaking at No. 45 on the Billboard Hot 100 and No. 11 on the Hot Rap Tracks chart. The single also earned Cypress Hill's third Grammy nomination. Shortly after the release of III: Temples of Boom, Sen Dog became frustrated due to the rigorous touring schedule. Just prior to an overseas tour, he departed from the group unexpectedly. Cypress Hill continued their tours throughout 1995 and 1996, with Eric Bobo and also various guest vocalists covering Sen Dog's verses. Sen Dog later formed the rock band SX-10 to explore other musical genres. Later on in 1996, Cypress Hill appeared on the first Smokin' Grooves tour, featuring Ziggy Marley, the Fugees, Busta Rhymes, and A Tribe Called Quest. The group also released a nine track EP, Unreleased and Revamped with rare mixes.

Focus on solo projects, IV, crossover appeal with Skull & Bones, and Stoned Raiders (1997–2002)
In 1997, the members focused on their solo careers. DJ Muggs released Soul Assassins: Chapter 1, with features from Dr. Dre, KRS-One, Wyclef Jean, and Mobb Deep. B-Real appeared with Busta Rhymes, Coolio, LL Cool J, and Method Man on "Hit 'Em High" from the multi-platinum Space Jam Soundtrack. He also appeared with RBX, Nas, and KRS-One on "East Coast Killer, West Coast Killer" from Dr. Dre's Dr. Dre Presents the Aftermath album, and contributed to an album entitled The Psycho Realm with the group of the same name. Sen Dog also released the Get Wood sampler as part of SX-10 on the label Flip Records. In addition, Eric Bobo contributed drums to various rock bands on their albums, such as 311 and Soulfly.

In early 1998, Sen Dog returned to Cypress Hill. He cited his therapist and also his creative collaborations with the band SX-10 as catalysts for his rejoining. The quartet then embarked on the third annual Smokin' Grooves tour with Public Enemy, Wyclef Jean, Busta Rhymes, and Gang Starr. Cypress Hill released IV in October 1998 which went gold in the U.S. and peaked at No. 11 on the Billboard 200. The lead single off the album was "Dr. Greenthumb", as it peaked at No. 11 on the Hot Rap Tracks chart. It also peaked at No. 70 on the Billboard Hot 100, their last appearance on the chart to date. In 1999, Cypress Hill helped with the PC first-person shooter video game Kingpin: Life of Crime. Three of the band's songs from the 1998 IV album were in the game; "16 Men Till There's No Men Left", "Checkmate", and "Lightning Strikes". The group also did voice work for some of the game's characters. Also in 1999, the band released a greatest hits album in Spanish, Los Grandes Éxitos en Español.

In 2000, Cypress Hill fused genres with their fifth album, Skull & Bones, which consisted of two discs. The first disc Skull was composed of rap tracks while Bones explored further the group's forays into rock. The album peaked at No. 5 on the Billboard 200 and at No. 3 on the Canadian Albums Chart, and the album was eventually certified platinum by the RIAA. The first two singles were "(Rock) Superstar" for rock radio and "(Rap) Superstar" for urban radio. Both singles received heavy airplay on both rock and urban radio, enabling Cypress Hill to crossover again. "(Rock) Superstar" peaked at No. 18 on the Modern Rock Tracks chart and "(Rap) Superstar" peaked at No. 43 on the Hot Rap Tracks chart.

Due to the rock genre's prominent appearance on Skull & Bones, Cypress Hill employed the members of Sen Dog's band SX-10 as backing musicians for the live shows. Cypress Hill supported Skull & Bones by initially playing a summer tour with Limp Bizkit and Cold called the Back 2 Basics Tour. The tour was controversial as it was sponsored by the file sharing service Napster. In addition, Napster enabled each show of the tour to be free to the fans, and no security guards were employed during the performances. After the tour's conclusion, the acts had not reported any disturbances. Towards the end of 2000, Cypress Hill and MxPx landed a slot opening for The Offspring on the Conspiracy of One Tour. The group also released Live at the Fillmore, a concert disc recorded at San Francisco's The Fillmore in 2000. Cypress Hill continued their experimentation with rock on the Stoned Raiders album in 2001; however, its sales were a disappointment. The album peaked at No. 64 on the Billboard 200, the group's lowest position to that point. Also in 2001, the group made a cameo appearance as themselves in the film How High. Cypress Hill then recorded the track "Just Another Victim" for WWF as a theme song for Tazz, borrowing elements from the 2000 single "(Rock) Superstar". The song would later be featured on the compilation WWF Forceable Entry in March 2002, which peaked at No. 3 on the Billboard 200 and was certified gold by the RIAA.

Till Death Do Us Part, DJ Muggs' hiatus, and extensive collaborations on Rise Up (2003–2012)
Cypress Hill released Till Death Do Us Part in March 2004 as it peaked at No. 21 on the Billboard 200. It featured appearances by Bob Marley's son Damian Marley, Prodigy of Mobb Deep, and producers The Alchemist and Fredwreck. The album represented a further departure from the group's signature sound. Reggae was a strong influence on its sound, especially on the lead single "What's Your Number?". The track featured Tim Armstrong of Rancid on guitar and backup vocals. It was based on the classic song "The Guns of Brixton" from The Clash's album London Calling. "What's Your Number?" saw Cypress Hill crossover into the rock charts again, as the single peaked at No. 23 on the Modern Rock Tracks chart.

Afterwards, DJ Muggs took a hiatus from the group to focus on other projects, such as Soul Assassins and his DJ Muggs vs. collaboration albums. In December 2005 another compilation album titled Greatest Hits From the Bong was released. It included nine hits from previous albums and two new tracks. In the summer of 2006, B-Real appeared on Snoop Dogg's single "Vato", which was produced by Pharrell Williams. The group's next album was tentatively scheduled for an early 2007 release, but it was pushed back numerous times. In 2007 Cypress Hill toured as a part of the Rock the Bells tour. They headlined with Public Enemy, Wu-Tang Clan, Nas, and a reunited Rage Against the Machine.

On July 25, 2008, Cypress Hill performed at a benefit concert at the House of Blues Chicago, where a majority of the proceeds went to the Chicago Alliance to End Homelessness. In August 2009, a new song by Cypress Hill titled "Get 'Em Up" was made available on iTunes. The song was also featured in the Madden NFL 2010 video game. It was the first sampling of the group's then-upcoming album. Cypress Hill's eighth studio album Rise Up featured contributions from Everlast, Tom Morello, Daron Malakian, Pitbull, Marc Anthony, and Mike Shinoda. Previously, the vast majority of the group's albums were produced by DJ Muggs; however, Rise Up instead featured a large array of guest features and producers, with DJ Muggs only appearing on two tracks. The album was released on Priority Records/EMI Entertainment, as the group was signed to the label by new creative chairman Snoop Dogg. Rise Up was released on April 20, 2010 and it peaked at No. 19 on the Billboard 200. The single "Rise Up" was featured at WWE's pay-per-view Elimination Chamber as the official theme song for the event. It also appeared in the trailer for the movie The Green Hornet. "Rise Up" managed to peak at No. 20 on both the Modern Rock Tracks and Mainstream Rock Tracks charts. "Armada Latina", which featured Pitbull and Marc Anthony, was Cypress Hill's last song to chart in the U.S. to date, peaking at No. 25 on the Hot Rap Tracks chart.

Cypress Hill commenced its Rise Up tour in Philadelphia on April 10, 2010. In one particular instance, the group was supposed to stop in Tucson, Arizona but canceled the show in protest of the recent immigration legislation. At the Rock en Seine festival in Paris on August 27, 2010, they had said in an interview that they would anticipate the outcome of the legislation before returning. Also in 2010, Cypress Hill performed at the Reading and Leeds Festivals on August 28 at Leeds and August 29 at Reading. On June 5, 2012, Cypress Hill and dubstep artist Rusko released a collaborative EP entitled Cypress X Rusko. DJ Muggs, who was still on a hiatus, and Eric Bobo were absent on the release. Also in 2012, Cypress Hill collaborated with Deadmau5 on his sixth studio album Album Title Goes Here, lending vocals on "Failbait".

Elephants on Acid, Hollywood Walk of Fame, and Back in Black (2013–2022)
During the interval between Cypress Hill albums, the four members commenced work on various projects. B-Real formed the band Prophets of Rage alongside three members of Rage Against the Machine and two members of Public Enemy. He also released The Prescription EP under his Dr. Greenthumb persona. Sen Dog formed the band Powerflo alongside members of Fear Factory, downset., and Biohazard. DJ Muggs revived his Soul Assassins project as its main producer. Eric Bobo formed a duo named Ritmo Machine. He also contributed to an unreleased album by his father Willie Bobo.

On September 28, 2018, Cypress Hill released the album Elephants on Acid, which saw the return of DJ Muggs as main composer and producer. It peaked at No. 120 on the Billboard 200 and at No. 6 on the Top Independent Albums chart. Overall, four different singles were released to promote the album. In April 2019 Cypress Hill received a star on the Hollywood Walk of Fame. Although various solo hip hop artists had received stars, Cypress Hill became the first collective hip hop group to receive a star. The entire lineup of B-Real, Sen Dog, Eric Bobo, and DJ Muggs had all attended the ceremony.

In January 2022, the group announced their 10th studio album entitled Back in Black. In addition, Cypress Hill planned to support the album by joining Slipknot alongside Ho99o9 for the second half of the 2022 Knotfest Roadshow. They had previously invited Slipknot to join their Great Smoke-Out festival back in 2009. Back in Black was released on March 18, 2022. It was the group's first album to not feature DJ Muggs on any of the tracks, as producing duties were handled by Black Milk. Back in Black was the lowest charting album of the group's career, and the first to not reach the Billboard 200 chart; however, it peaked at No. 69 on the Top Current Album Sales chart.

A documentary about the group, entitled Cypress Hill: Insane in the Brain, was released on the Showtime service in April 2022. Estevan Oriol, Cypress Hill's former tour manager and close associate, directed the film. It had mainly chronicled the group's formation and their first decade of existence. In relation to the Cypress Hill: Insane in the Brain documentary, Cypress Hill digitally released the single "Crossroads" in September 2022. The single featured the return of DJ Muggs on production.

Future plans and tentative final album (2023–present)
In an interview, Sen Dog claimed that the group will fully reunite with DJ Muggs for an 11th album; however, he stated that it will be the group's final album of their career.

The group performed at various festivals in 2023 such as the Festival d'été de Québec and in celebrating the 30th anniversary of their second studio album Black Sunday, they also announced several standalone concerts in North America and Europe. They also performed alongside The Pharcyde and Souls of Mischief in May 2024. In March 2024, they announced three dates in Italy, Austria, and Germany for July.

In a callback to Cypress Hill's appearance in the "Homerpalooza" Simpsons episode in 1996 (which contained a skit of the group realizing they must have ordered the London Symphony Orchestra while high to perform with), it was announced that the group would actually perform with the London Symphony Orchestra at London's Royal Albert Hall in July 2024.

Rapping
One of the band's most striking aspects is B-Real's exaggeratedly high-pitched nasal vocals. In the book Check the Technique, B-Real described his nasal style, saying his rapping voice is "high and annoying...the nasal style I have was just something that I developed...my more natural style wasn't so pleasing to DJ Muggs and Sen Dog's ears" and talking about the nasal style in the book How to Rap, B-Real said "you want to stand out from the others and just be distinct...when you got something that can separate you from everybody else, you gotta use it to your advantage." In the film Art of Rap, B-Real credited the Beastie Boys as an influence when developing his rapping style. Sen Dog's voice is deeper, more violent, and often shouted alongside the rapping; his vocals are often emphasized by adding another background/choir voice to say them. Sen Dog's style is in contrast to B-Real's, who said "Sen's voice is so strong" and "it all blends together" when they are both on the same track.

Both B-Real and Sen Dog started writing lyrics in both Spanish and English. Initially, B-Real was inspired to start writing raps from watching Sen Dog and Mellow Man Ace writing their lyrics, and originally B-Real was going to just be the writer for the group rather than a rapper. Their lyrics are noted for bringing a "cartoonish" approach to violence by Peter Shapiro and Allmusic.

Production
The sound and groove of their music, mostly produced by DJ Muggs, has spooky sounds and a stoned aesthetic; with its bass-heavy rhythms and odd sample loops ("Insane in the Brain" has a blues guitar pitched looped in its chorus), it carries a psychedelic value, which is lessened in their rock-oriented albums. The double album Skull & Bones consists of a pure rap disc (Skull) and a separate rock disc (Bones). In the live album Live at The Fillmore, some of the old classics were played in a rock/metal version, with Eric Bobo playing the drums and Sen Dog's band SX-10 as the other instrumentalists. 2010's Rise Up was the most radically different album in regards to production. DJ Muggs had produced the majority of each prior Cypress Hill album, but he only appeared on Rise Up twice. The remaining songs were handled by various other guests. 2018's Elephants on Acid marked the return of DJ Muggs, and the album featured a more psychedelic and hip-hop approach.

Legacy
Cypress Hill are often credited for being one of the few Latin American hip hop groups to break through with their own stylistic impact on rap music, in addition to finding a crossover audience among the rock community. Cypress Hill have been cited as an influence by artists such as Eminem, Baby Bash, Paul Wall ,Post Malone, Luniz, and Fat Joe. Cypress Hill have also been cited as a strong influence on nu metal bands such as Deftones, Limp Bizkit, System of a Down, Linkin Park, and Korn. Famously, the bassline during the outro of Korn's 1994 single "Blind" was a direct tribute to Cypress Hill's 1993 track "Lick a Shot".

Studio albums

 * Cypress Hill (1991)
 * Black Sunday (1993)
 * III: Temples of Boom (1995)
 * IV (1998)
 * Skull & Bones (2000)
 * Stoned Raiders (2001)
 * Till Death Do Us Part (2004)
 * Rise Up (2010)
 * Elephants on Acid (2018)
 * Back in Black (2022)

Awards and nominations
Billboard Music Awards

Grammy Awards

MTV Video Music Awards

Hollywood Walk of Fame

 * 2019
 * Cypress Hill
 * Star
 * Won
 * Won

 * }

Members
Current Current touring
 * Louis "B-Real" Freese – vocals (1988–present)
 * Senen "Sen Dog" Reyes – vocals (1988–1995, 1998–present)
 * Eric "Eric Bobo" Correa – drums, percussion (1994–present)
 * Lawrence "DJ Muggs" Muggerud – turntables, samples (1988–2004, 2014–present)
 * Lord "DJ Lord" Asword – turntables, samples, vocals (2019–present)

Former Former touring
 * Ulpiano "Mellow Man Ace" Reyes – vocals (1988)
 * Panchito "Ponch" Gomez – drums, percussion (1993–1994)
 * Frank Mercurio – bass (2000–2002)
 * Jeremy Fleener – guitar (2000–2002)
 * Andy Zambrano – guitar (2000–2002)
 * Julio "Julio G" González – turntables, samples (2004–2014)
 * Michael "Mix Master Mike" Schwartz – turntables, samples (2018–2019)

 * Timeline

title: Cypress Hill


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Combustion

Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While activation energy must be supplied to initiate combustion (e.g., using a lit match to light a fire), the heat from a flame may provide enough energy to make the reaction self-sustaining. The study of combustion is known as combustion science.

Combustion is often a complicated sequence of elementary radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot enough that incandescent light in the form of either glowing or a flame is produced. A simple example can be seen in the combustion of hydrogen and oxygen into water vapor, a reaction which is commonly used to fuel rocket engines. This reaction releases 242kJ/mol of heat and reduces the enthalpy accordingly (at constant temperature and pressure):

Uncatalyzed combustion in air requires relatively high temperatures. Complete combustion is stoichiometric concerning the fuel, where there is no remaining fuel, and ideally, no residual oxidant. Thermodynamically, the chemical equilibrium of combustion in air is overwhelmingly on the side of the products. However, complete combustion is almost impossible to achieve, since the chemical equilibrium is not necessarily reached, or may contain unburnt products such as carbon monoxide, hydrogen and even carbon (soot or ash). Thus, the produced smoke is usually toxic and contains unburned or partially oxidized products. Any combustion at high temperatures in atmospheric air, which is 78 percent nitrogen, will also create small amounts of several nitrogen oxides, commonly referred to as NOx, since the combustion of nitrogen is thermodynamically favored at high, but not low temperatures. Since burning is rarely clean, fuel gas cleaning or catalytic converters may be required by law.

Fires occur naturally, ignited by lightning strikes or by volcanic products. Combustion (fire) was the first controlled chemical reaction discovered by humans, in the form of campfires and bonfires, and continues to be the main method to produce energy for humanity. Usually, the fuel is carbon, hydrocarbons, or more complicated mixtures such as wood that contain partially oxidized hydrocarbons. The thermal energy produced from the combustion of either fossil fuels such as coal or oil, or from renewable fuels such as firewood, is harvested for diverse uses such as cooking, production of electricity or industrial or domestic heating. Combustion is also currently the only reaction used to power rockets. Combustion is also used to destroy (incinerate) waste, both nonhazardous and hazardous.

Oxidants for combustion have high oxidation potential and include atmospheric or pure oxygen, chlorine, fluorine, chlorine trifluoride, nitrous oxide and nitric acid. For instance, hydrogen burns in chlorine to form hydrogen chloride with the liberation of heat and light characteristic of combustion. Although usually not catalyzed, combustion can be catalyzed by platinum or vanadium, as in the contact process.

Complete
In complete combustion, the reactant burns in oxygen and produces a limited number of products. When a hydrocarbon burns in oxygen, the reaction will primarily yield carbon dioxide and water. When elements are burned, the products are primarily the most common oxides. Carbon will yield carbon dioxide, sulfur will yield sulfur dioxide, and iron will yield iron(III) oxide. Nitrogen is not considered to be a combustible substance when oxygen is the oxidant. Still, small amounts of various nitrogen oxides (commonly designated NOx species) form when the air is the oxidative.

Combustion is not necessarily favorable to the maximum degree of oxidation, and it can be temperature-dependent. For example, sulfur trioxide is not produced quantitatively by the combustion of sulfur. species appear in significant amounts above about 2800 F, and more is produced at higher temperatures. The amount of is also a function of oxygen excess.

In most industrial applications and in fires, air is the source of oxygen. In the air, each mole of oxygen is mixed with approximately $3.71 mol$ of nitrogen. Nitrogen does not take part in combustion, but at high temperatures, some nitrogen will be converted to NOx (mostly Nitric oxide, with much smaller amounts of Nitrogen dioxide). On the other hand, when there is insufficient oxygen to combust the fuel completely, some fuel carbon is converted to carbon monoxide, and some of the hydrogens remain unreacted. A complete set of equations for the combustion of a hydrocarbon in the air, therefore, requires an additional calculation for the distribution of oxygen between the carbon and hydrogen in the fuel.

The amount of air required for complete combustion is known as the "theoretical air" or "stoichiometric air". The amount of air above this value actually needed for optimal combustion is known as the "excess air", and can vary from 5% for a natural gas boiler, to 40% for anthracite coal, to 300% for a gas turbine.

Incomplete
Incomplete combustion will occur when there is not enough oxygen to allow the fuel to react completely to produce carbon dioxide and water. It also happens when the combustion is quenched by a heat sink, such as a solid surface or flame trap. As is the case with complete combustion, water is produced by incomplete combustion; however, carbon and carbon monoxide are produced instead of carbon dioxide.

For most fuels, such as diesel oil, coal, or wood, pyrolysis occurs before combustion. In incomplete combustion, products of pyrolysis remain unburnt and contaminate the smoke with noxious particulate matter and gases. Partially oxidized compounds are also a concern; partial oxidation of ethanol can produce harmful acetaldehyde, and carbon can produce toxic carbon monoxide.

The designs of combustion devices can improve the quality of combustion, such as burners and internal combustion engines. Further improvements are achievable by catalytic after-burning devices (such as catalytic converters) or by the simple partial return of the exhaust gases into the combustion process. Such devices are required by environmental legislation for cars in most countries. They may be necessary to enable large combustion devices, such as thermal power stations, to reach legal emission standards.

The degree of combustion can be measured and analyzed with test equipment. HVAC contractors, firefighters and engineers use combustion analyzers to test the efficiency of a burner during the combustion process. Also, the efficiency of an internal combustion engine can be measured in this way, and some U.S. states and local municipalities use combustion analysis to define and rate the efficiency of vehicles on the road today.

Carbon monoxide is one of the products from incomplete combustion. The formation of carbon monoxide produces less heat than formation of carbon dioxide so complete combustion is greatly preferred especially as carbon monoxide is a poisonous gas. When breathed, carbon monoxide takes the place of oxygen and combines with some of the hemoglobin in the blood, rendering it unable to transport oxygen.

Environmental problems
These oxides combine with water and oxygen in the atmosphere, creating nitric acid and sulfuric acids, which return to Earth's surface as acid deposition, or "acid rain." Acid deposition harms aquatic organisms and kills trees. Due to its formation of certain nutrients that are less available to plants such as calcium and phosphorus, it reduces the productivity of the ecosystem and farms. An additional problem associated with nitrogen oxides is that they, along with hydrocarbon pollutants, contribute to the formation of ground level ozone, a major component of smog.

Human health problems
Breathing carbon monoxide causes headache, dizziness, vomiting, and nausea. If carbon monoxide levels are high enough, humans become unconscious or die. Exposure to moderate and high levels of carbon monoxide over long periods is positively correlated with the risk of heart disease. People who survive severe carbon monoxide poisoning may suffer long-term health problems. Carbon monoxide from the air is absorbed in the lungs which then binds with hemoglobin in human's red blood cells. This reduces the capacity of red blood cells that carry oxygen throughout the body.

Smoldering
Smoldering is the slow, low-temperature, flameless form of combustion, sustained by the heat evolved when oxygen directly attacks the surface of a condensed-phase fuel. It is a typically incomplete combustion reaction. Solid materials that can sustain a smoldering reaction include coal, cellulose, wood, cotton, tobacco, peat, duff, humus, synthetic foams, charring polymers (including polyurethane foam) and dust. Common examples of smoldering phenomena are the initiation of residential fires on upholstered furniture by weak heat sources (e.g., a cigarette, a short-circuited wire) and the persistent combustion of biomass behind the flaming fronts of wildfires.

Spontaneous
Spontaneous combustion is a type of combustion that occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self-heating which rapidly accelerates to high temperatures) and finally, ignition. For example, phosphorus self-ignites at room temperature without the application of heat. Organic materials undergoing bacterial composting can generate enough heat to reach the point of combustion.

Turbulent
Combustion resulting in a turbulent flame is the most used for industrial applications (e.g. gas turbines, gasoline engines, etc.) because the turbulence helps the mixing process between the fuel and oxidizer.

Micro-gravity

The term 'micro' gravity refers to a gravitational state that is 'low' (i.e., 'micro' in the sense of 'small' and not necessarily a millionth of Earth's normal gravity) such that the influence of buoyancy on physical processes may be considered small relative to other flow processes that would be present at normal gravity. In such an environment, the thermal and flow transport dynamics can behave quite differently than in normal gravity conditions (e.g., a candle's flame takes the shape of a sphere. ). Microgravity combustion research contributes to the understanding of a wide variety of aspects that are relevant to both the environment of a spacecraft (e.g., fire dynamics relevant to crew safety on the International Space Station) and terrestrial (Earth-based) conditions (e.g., droplet combustion dynamics to assist developing new fuel blends for improved combustion, materials fabrication processes, thermal management of electronic systems, multiphase flow boiling dynamics, and many others).

Micro-combustion
Combustion processes that happen in very small volumes are considered micro-combustion. The high surface-to-volume ratio increases specific heat loss. Quenching distance plays a vital role in stabilizing the flame in such combustion chambers.

Stoichiometric combustion of a hydrocarbon in oxygen
Generally, the chemical equation for stoichiometric combustion of a hydrocarbon in oxygen is:

For example, the stoichiometric combustion of methane in oxygen is:

Stoichiometric combustion of a hydrocarbon in air
If the stoichiometric combustion takes place using air as the oxygen source, the nitrogen present in the air (Atmosphere of Earth) can be added to the equation (although it does not react) to show the stoichiometric composition of the fuel in air and the composition of the resultant flue gas. Treating all non-oxygen components in air as nitrogen gives a 'nitrogen' to oxygen ratio of 3.77, i.e. (100% - O2%) / O2% where O2% is 20.95% vol:

where $$z = x + {y\over 4}$$.

For example, the stoichiometric combustion of methane in air is:

The stoichiometric composition of methane in air is 1 / (1 + 2 + 7.54) = 9.49% vol.

The stoichiometric combustion reaction for C$α$H$β$O$γ$ in air:

The stoichiometric combustion reaction for C$α$H$β$O$γ$S$δ$:

The stoichiometric combustion reaction for C$α$H$β$O$γ$N$δ$S$ε$:

The stoichiometric combustion reaction for C$α$H$β$O$γ$F$δ$:

Trace combustion products
Various other substances begin to appear in significant amounts in combustion products when the flame temperature is above about $1,600 K$. When excess air is used, nitrogen may oxidize to and, to a much lesser extent, to. forms by disproportionation of, and and  form by disproportionation of.

For example, when $1 mol$ of propane is burned with $28.6 mol$ of air (120% of the stoichiometric amount), the combustion products contain 3.3%. At $1,400 K$, the equilibrium combustion products contain 0.03% and 0.002%. At $1,800 K$, the combustion products contain 0.17%, 0.05% , 0.01% , and 0.004%.

Diesel engines are run with an excess of oxygen to combust small particles that tend to form with only a stoichiometric amount of oxygen, necessarily producing nitrogen oxide emissions. Both the United States and European Union enforce limits to vehicle nitrogen oxide emissions, which necessitate the use of special catalytic converters or treatment of the exhaust with urea (see Diesel exhaust fluid).

Incomplete combustion of a hydrocarbon in oxygen
The incomplete (partial) combustion of a hydrocarbon with oxygen produces a gas mixture containing mainly, , , and. Such gas mixtures are commonly prepared for use as protective atmospheres for the heat-treatment of metals and for gas carburizing. The general reaction equation for incomplete combustion of one mole of a hydrocarbon in oxygen is:

When z falls below roughly 50% of the stoichiometric value, Methane can become an important combustion product; when z falls below roughly 35% of the stoichiometric value, elemental carbon may become stable.

The products of incomplete combustion can be calculated with the aid of a material balance, together with the assumption that the combustion products reach equilibrium. For example, in the combustion of one mole of propane with four moles of, seven moles of combustion gas are formed, and z is 80% of the stoichiometric value. The three elemental balance equations are:
 * Carbon: $$a + b = 3$$
 * Hydrogen: $$2c + 2d = 8$$
 * Oxygen: $$2a + b + c = 8$$

These three equations are insufficient in themselves to calculate the combustion gas composition. However, at the equilibrium position, the water-gas shift reaction gives another equation:

 * ; $$K_{eq} = \frac{a \times d}{b \times c}$$

For example, at $1,200 K$ the value of K$eq$ is 0.728. Solving, the combustion gas consists of 42.4%, 29.0% , 14.7% , and 13.9%. Carbon becomes a stable phase at $1,200 K$ and $1 atm$ pressure when z is less than 30% of the stoichiometric value, at which point the combustion products contain more than 98% and  and about 0.5%.

Substances or materials which undergo combustion are called fuels. The most common examples are natural gas, propane, kerosene, diesel, petrol, charcoal, coal, wood, etc.

Liquid fuels
Combustion of a liquid fuel in an oxidizing atmosphere actually happens in the gas phase. It is the vapor that burns, not the liquid. Therefore, a liquid will normally catch fire only above a certain temperature: its flash point. The flash point of liquid fuel is the lowest temperature at which it can form an ignitable mix with air. It is the minimum temperature at which there is enough evaporated fuel in the air to start combustion.

Gaseous fuels
Combustion of gaseous fuels may occur through one of four distinctive types of burning: diffusion flame, premixed flame, autoignitive reaction front, or as a detonation. The type of burning that actually occurs depends on the degree to which the fuel and oxidizer are mixed prior to heating: for example, a diffusion flame is formed if the fuel and oxidizer are separated initially, whereas a premixed flame is formed otherwise. Similarly, the type of burning also depends on the pressure: a detonation, for example, is an autoignitive reaction front coupled to a strong shock wave giving it its characteristic high-pressure peak and high detonation velocity.

Solid fuels

The act of combustion consists of three relatively distinct but overlapping phases:
 * Preheating phase, when the unburned fuel is heated up to its flash point and then fire point. Flammable gases start being evolved in a process similar to dry distillation.
 * Distillation phase or gaseous phase, when the mix of evolved flammable gases with oxygen is ignited. Energy is produced in the form of heat and light. Flames are often visible. Heat transfer from the combustion to the solid maintains the evolution of flammable vapours.
 * Charcoal phase or solid phase, when the output of flammable gases from the material is too low for the persistent presence of flame and the charred fuel does not burn rapidly and just glows and later only smoulders.

Combustion management
Efficient process heating requires recovery of the largest possible part of a fuel's heat of combustion into the material being processed. There are many avenues of loss in the operation of a heating process. Typically, the dominant loss is sensible heat leaving with the offgas (i.e., the flue gas). The temperature and quantity of offgas indicates its heat content (enthalpy), so keeping its quantity low minimizes heat loss.

In a perfect furnace, the combustion air flow would be matched to the fuel flow to give each fuel molecule the exact amount of oxygen needed to cause complete combustion. However, in the real world, combustion does not proceed in a perfect manner. Unburned fuel (usually and ) discharged from the system represents a heating value loss (as well as a safety hazard). Since combustibles are undesirable in the offgas, while the presence of unreacted oxygen there presents minimal safety and environmental concerns, the first principle of combustion management is to provide more oxygen than is theoretically needed to ensure that all the fuel burns. For methane combustion, for example, slightly more than two molecules of oxygen are required.

The second principle of combustion management, however, is to not use too much oxygen. The correct amount of oxygen requires three types of measurement: first, active control of air and fuel flow; second, offgas oxygen measurement; and third, measurement of offgas combustibles. For each heating process, there exists an optimum condition of minimal offgas heat loss with acceptable levels of combustibles concentration. Minimizing excess oxygen pays an additional benefit: for a given offgas temperature, the NOx level is lowest when excess oxygen is kept lowest.

Adherence to these two principles is furthered by making material and heat balances on the combustion process. The material balance directly relates the air/fuel ratio to the percentage of in the combustion gas. The heat balance relates the heat available for the charge to the overall net heat produced by fuel combustion. Additional material and heat balances can be made to quantify the thermal advantage from preheating the combustion air, or enriching it in oxygen.

Reaction mechanism
Combustion in oxygen is a chain reaction in which many distinct radical intermediates participate. The high energy required for initiation is explained by the unusual structure of the dioxygen molecule. The lowest-energy configuration of the dioxygen molecule is a stable, relatively unreactive diradical in a triplet spin state. Bonding can be described with three bonding electron pairs and two antibonding electrons, with spins aligned, such that the molecule has nonzero total angular momentum. Most fuels, on the other hand, are in a singlet state, with paired spins and zero total angular momentum. Interaction between the two is quantum mechanically a "forbidden transition", i.e. possible with a very low probability. To initiate combustion, energy is required to force dioxygen into a spin-paired state, or singlet oxygen. This intermediate is extremely reactive. The energy is supplied as heat, and the reaction then produces additional heat, which allows it to continue.

Combustion of hydrocarbons is thought to be initiated by hydrogen atom abstraction (not proton abstraction) from the fuel to oxygen, to give a hydroperoxide radical (HOO). This reacts further to give hydroperoxides, which break up to give hydroxyl radicals. There are a great variety of these processes that produce fuel radicals and oxidizing radicals. Oxidizing species include singlet oxygen, hydroxyl, monatomic oxygen, and hydroperoxyl. Such intermediates are short-lived and cannot be isolated. However, non-radical intermediates are stable and are produced in incomplete combustion. An example is acetaldehyde produced in the combustion of ethanol. An intermediate in the combustion of carbon and hydrocarbons, carbon monoxide, is of special importance because it is a poisonous gas, but also economically useful for the production of syngas.

Solid and heavy liquid fuels also undergo a great number of pyrolysis reactions that give more easily oxidized, gaseous fuels. These reactions are endothermic and require constant energy input from the ongoing combustion reactions. A lack of oxygen or other improperly designed conditions result in these noxious and carcinogenic pyrolysis products being emitted as thick, black smoke.

The rate of combustion is the amount of a material that undergoes combustion over a period of time. It can be expressed in grams per second (g/s) or kilograms per second (kg/s).

Detailed descriptions of combustion processes, from the chemical kinetics perspective, require the formulation of large and intricate webs of elementary reactions. For instance, combustion of hydrocarbon fuels typically involve hundreds of chemical species reacting according to thousands of reactions.

The inclusion of such mechanisms within computational flow solvers still represents a pretty challenging task mainly in two aspects. First, the number of degrees of freedom (proportional to the number of chemical species) can be dramatically large; second, the source term due to reactions introduces a disparate number of time scales which makes the whole dynamical system stiff. As a result, the direct numerical simulation of turbulent reactive flows with heavy fuels soon becomes intractable even for modern supercomputers.

Therefore, a plethora of methodologies have been devised for reducing the complexity of combustion mechanisms without resorting to high detail levels. Examples are provided by:
 * The Relaxation Redistribution Method (RRM)
 * The Intrinsic Low-Dimensional Manifold (ILDM) approach and further developments
 * The invariant-constrained equilibrium edge preimage curve method.
 * A few variational approaches
 * The Computational Singular perturbation (CSP) method and further developments.
 * The Rate Controlled Constrained Equilibrium (RCCE) and Quasi Equilibrium Manifold (QEM) approach.
 * The G-Scheme.
 * The Method of Invariant Grids (MIG).

Kinetic modelling
The kinetic modelling may be explored for insight into the reaction mechanisms of thermal decomposition in the combustion of different materials by using for instance Thermogravimetric analysis.

Temperature
Assuming perfect combustion conditions, such as complete combustion under adiabatic conditions (i.e., no heat loss or gain), the adiabatic combustion temperature can be determined. The formula that yields this temperature is based on the first law of thermodynamics and takes note of the fact that the heat of combustion is used entirely for heating the fuel, the combustion air or oxygen, and the combustion product gases (commonly referred to as the flue gas).

In the case of fossil fuels burnt in air, the combustion temperature depends on all of the following:
 * the heating value;
 * the stoichiometric air to fuel ratio $${\lambda}$$;
 * the specific heat capacity of fuel and air;
 * the air and fuel inlet temperatures.

The adiabatic combustion temperature (also known as the adiabatic flame temperature) increases for higher heating values and inlet air and fuel temperatures and for stoichiometric air ratios approaching one.

Most commonly, the adiabatic combustion temperatures for coals are around 2200 C (for inlet air and fuel at ambient temperatures and for $$\lambda = 1.0$$), around 2150 C for oil and 2000 C for natural gas.

In industrial fired heaters, power station steam generators, and large gas-fired turbines, the more common way of expressing the usage of more than the stoichiometric combustion air is percent excess combustion air. For example, excess combustion air of 15 percent means that 15 percent more than the required stoichiometric air is being used.

Instabilities
Combustion instabilities are typically violent pressure oscillations in a combustion chamber. These pressure oscillations can be as high as 180dB, and long-term exposure to these cyclic pressure and thermal loads reduces the life of engine components. In rockets, such as the F1 used in the Saturn V program, instabilities led to massive damage to the combustion chamber and surrounding components. This problem was solved by re-designing the fuel injector. In liquid jet engines, the droplet size and distribution can be used to attenuate the instabilities. Combustion instabilities are a major concern in ground-based gas turbine engines because of emissions. The tendency is to run lean, an equivalence ratio less than 1, to reduce the combustion temperature and thus reduce the emissions; however, running the combustion lean makes it very susceptible to combustion instability.

The Rayleigh Criterion is the basis for analysis of thermoacoustic combustion instability and is evaluated using the Rayleigh Index over one cycle of instability

$$G(x)=\frac{1}{T}\int_{T}q'(x,t)p'(x,t)dt$$

where q' is the heat release rate perturbation and p' is the pressure fluctuation. When the heat release oscillations are in phase with the pressure oscillations, the Rayleigh Index is positive and the magnitude of the thermoacoustic instability is maximised. On the other hand, if the Rayleigh Index is negative, then thermoacoustic damping occurs. The Rayleigh Criterion implies that thermoacoustic instability can be optimally controlled by having heat release oscillations 180 degrees out of phase with pressure oscillations at the same frequency. This minimizes the Rayleigh Index.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Combustion


text:
Cyrillic script

The Cyrillic script, Slavonic script or simply Slavic script is a writing system used for various languages across Eurasia. It is the designated national script in various Slavic, Turkic, Mongolic, Uralic, Caucasian and Iranic-speaking countries in Southeastern Europe, Eastern Europe, the Caucasus, Central Asia, North Asia, and East Asia, and used by many other minority languages.

, around 250 million people in Eurasia use Cyrillic as the official script for their national languages, with Russia accounting for about half of them. With the accession of Bulgaria to the European Union on 1 January 2007, Cyrillic became the third official script of the European Union, following the Latin and Greek alphabets.

The Early Cyrillic alphabet was developed during the 9th century AD at the Preslav Literary School in the First Bulgarian Empire during the reign of Tsar Simeon I the Great, probably by the disciples of the two Byzantine brothers Cyril and Methodius, who had previously created the Glagolitic script. Among them were Clement of Ohrid, Naum of Preslav, Constantine of Preslav, Joan Ekzarh, Chernorizets Hrabar, Angelar, Sava and other scholars. The script is named in honor of Saint Cyril.

Etymology
Since the script was conceived and popularised by the followers of Cyril and Methodius in Bulgaria, rather than by Cyril and Methodius themselves, its name denotes homage rather than authorship.

History
The Cyrillic script was created during the First Bulgarian Empire. Modern scholars believe that the Early Cyrillic alphabet was created at the Preslav Literary School, the most important early literary and cultural center of the First Bulgarian Empire and of all Slavs: "Unlike the Churchmen in Ohrid, Preslav scholars were much more dependent upon Greek models and quickly abandoned the Glagolitic scripts in favor of an adaptation of the Greek uncial to the needs of Slavic, which is now known as the Cyrillic alphabet."

A number of prominent Bulgarian writers and scholars worked at the school, including Naum of Preslav until 893; Constantine of Preslav; Joan Ekzarh (also transcr. John the Exarch); and Chernorizets Hrabar, among others. The school was also a center of translation, mostly of Byzantine authors. The Cyrillic script is derived from the Greek uncial script letters, augmented by ligatures and consonants from the older Glagolitic alphabet for sounds not found in Greek. Glagolitic and Cyrillic were formalized by the Byzantine Saints Cyril and Methodius and their Bulgarian disciples, such as Saints Naum, Clement, Angelar, and Sava. They spread and taught Christianity in the whole of Bulgaria. Paul Cubberley posits that although Cyril may have codified and expanded Glagolitic, it was his students in the First Bulgarian Empire under Tsar Simeon the Great that developed Cyrillic from the Greek letters in the 890s as a more suitable script for church books.

Cyrillic spread among other Slavic peoples, as well as among non-Slavic Romanians. The earliest datable Cyrillic inscriptions have been found in the area of Preslav, in the medieval city itself and at nearby Patleina Monastery, both in present-day Shumen Province, as well as in the Ravna Monastery and in the Varna Monastery. The new script became the basis of alphabets used in various languages in Orthodox Church-dominated Eastern Europe, both Slavic and non-Slavic languages (such as Romanian, until the 1860s). For centuries, Cyrillic was also used by Catholic and Muslim Slavs (see Bosnian Cyrillic).

Cyrillic and Glagolitic were used for the Church Slavonic language, especially the Old Church Slavonic variant. Hence expressions such as "И is the tenth Cyrillic letter" typically refer to the order of the Church Slavonic alphabet; not every Cyrillic alphabet uses every letter available in the script. The Cyrillic script came to dominate Glagolitic in the 12th century.

The literature produced in Old Church Slavonic soon spread north from Bulgaria and became the lingua franca of the Balkans and Eastern Europe.

Bosnian Cyrillic, widely known as Bosančica is an extinct variant of the Cyrillic alphabet that originated in medieval Bosnia. Paleographers consider the earliest features of Bosnian Cyrillic script had likely begun to appear between the 10th or 11th century, with the Humac tablet (a tablet written in Bosnian Cyrillic) to be the first such document using this type of script and is believed to date from this period. Bosnian Cyrillic was used continuously until the 18th century, with sporadic usage even taking place in the 20th century.

With the orthographic reform of Saint Evtimiy of Tarnovo and other prominent representatives of the Tarnovo Literary School of the 14th and 15th centuries, such as Gregory Tsamblak and Constantine of Kostenets, the school influenced Russian, Serbian, Wallachian and Moldavian medieval culture. This is known in Russia as the second South-Slavic influence.

In 1708–10, the Cyrillic script used in Russia was heavily reformed by Peter the Great, who had recently returned from his Grand Embassy in Western Europe. The new letterforms, called the Civil script, became closer to those of the Latin alphabet; several archaic letters were abolished and several new letters were introduced designed by Peter himself. Letters became distinguished between upper and lower case. West European typography culture was also adopted. The pre-reform letterforms, called 'Полуустав', were notably retained in Church Slavonic and are sometimes used in Russian even today, especially if one wants to give a text a 'Slavic' or 'archaic' feel.

The alphabet used for the modern Church Slavonic language in Eastern Orthodox and Eastern Catholic rites still resembles early Cyrillic. However, over the course of the following millennium, Cyrillic adapted to changes in spoken language, developed regional variations to suit the features of national languages, and was subjected to academic reform and political decrees. A notable example of such linguistic reform can be attributed to Vuk Stefanović Karadžić, who updated the Serbian Cyrillic alphabet by removing certain graphemes no longer represented in the vernacular and introducing graphemes specific to Serbian (i.e. Љ Њ Ђ Ћ Џ Ј), distancing it from the Church Slavonic alphabet in use prior to the reform. Today, many languages in the Balkans, Eastern Europe, and northern Eurasia are written in Cyrillic alphabets.

Letters
Cyrillic script spread throughout the East Slavic and some South Slavic territories, being adopted for writing local languages, such as Old East Slavic. Its adaptation to local languages produced a number of Cyrillic alphabets, discussed below.

Majuscule and minuscule
Capital and lowercase letters were not distinguished in old manuscripts.

Yeri was originally a ligature of Yer and I ( +  = ). Iotation was indicated by ligatures formed with the letter І: (not an ancestor of modern Ya, Я, which is derived from ),,  (ligature of  and ), ,. Sometimes different letters were used interchangeably, for example =  =, as were typographical variants like  =. There were also commonly used ligatures like =.

Numbers
The letters also had numeric values, based not on Cyrillic alphabetical order, but inherited from the letters' Greek ancestors.

Computer support
Computer fonts for early Cyrillic alphabets are not routinely provided. Many of the letterforms differ from those of modern Cyrillic, varied a great deal between manuscripts, and changed over time. In accordance with Unicode policy, the standard does not include letterform variations or ligatures found in manuscript sources unless they can be shown to conform to the Unicode definition of a character: this aspect is the responsibility of the typeface designer.

The Unicode 5.1 standard, released on 4 April 2008, greatly improved computer support for the early Cyrillic and the modern Church Slavonic language. In Microsoft Windows, the Segoe UI user interface font is notable for having complete support for the archaic Cyrillic letters since Windows 8.

Currency signs
Some currency signs have derived from Cyrillic letters:
 * The Ukrainian hryvnia sign (₴) is from the cursive minuscule Ukrainian Cyrillic letter He (г ).
 * The Russian ruble sign (₽) from the majuscule Р.
 * The Kyrgyzstani som sign (⃀) from the majuscule С (es)
 * The Kazakhstani tenge sign (₸) from Т
 * The Mongolian tögrög sign (₮) from Т

Letterforms and type design
The development of Cyrillic letter forms passed directly from the medieval stage to the late Baroque, without a Renaissance phase as in Western Europe. Late Medieval Cyrillic letters (categorized as vyaz' and still found on many icon inscriptions today) show a marked tendency to be very tall and narrow, with strokes often shared between adjacent letters.

Peter the Great, Tsar of Russia, mandated the use of westernized letter forms (ru) in the early 18th century. Over time, these were largely adopted in the other languages that use the script. Thus, unlike the majority of modern Greek typefaces that retained their own set of design principles for lower-case letters (such as the placement of serifs, the shapes of stroke ends, and stroke-thickness rules, although Greek capital letters do use Latin design principles), modern Cyrillic types are much the same as modern Latin types of the same typeface family. The development of some Cyrillic computer fonts from Latin ones has also contributed to a visual Latinization of Cyrillic type.

Lowercase forms
Cyrillic uppercase and lowercase letter forms are not as differentiated as in Latin typography. Upright Cyrillic lowercase letters are essentially small capitals (with exceptions: Cyrillic $\langleа\rangle$, $\langleе\rangle$, $\langleі\rangle$, $\langleј\rangle$, $\langleр\rangle$, and $\langleу\rangle$ adopted Western lowercase shapes, lowercase $\langleф\rangle$ is typically designed under the influence of Latin $\langlep\rangle$, lowercase $\langleб\rangle$, $\langleђ\rangle$ and $\langleћ\rangle$ are traditional handwritten forms), although a good-quality Cyrillic typeface will still include separate small-caps glyphs.

Cyrillic typefaces, as well as Latin ones, have roman and italic forms (practically all popular modern computer fonts include parallel sets of Latin and Cyrillic letters, where many glyphs, uppercase as well as lowercase, are shared by both). However, the native typeface terminology in most Slavic languages (for example, in Russian) does not use the words "roman" and "italic" in this sense. Instead, the nomenclature follows German naming patterns:

 * Roman type is called pryamoy shrift ("upright type") – compare with Normalschrift ("regular type") in German
 * Italic type is called kursiv ("cursive") or kursivniy shrift ("cursive type") – from the German word Kursive, meaning italic typefaces and not cursive writing
 * Cursive handwriting is rukopisniy shrift ("handwritten type") – in German: Kurrentschrift or Laufschrift, both meaning literally 'running type'
 * A (mechanically) sloped oblique type of sans-serif faces is naklonniy shrift ("sloped" or "slanted type").
 * A boldfaced type is called poluzhirniy shrift ("semi-bold type"), because there existed fully boldfaced shapes that have been out of use since the beginning of the 20th century.

Italic and cursive forms
Similarly to Latin typefaces, italic and cursive forms of many Cyrillic letters (typically lowercase; uppercase only for handwritten or stylish types) are very different from their upright roman types. In certain cases, the correspondence between uppercase and lowercase glyphs does not coincide in Latin and Cyrillic types: for example, italic Cyrillic $\langleт\rangle$ is the lowercase counterpart of $\langleТ\rangle$ not of $\langleМ\rangle$.

Note: in some typefaces or styles, $\langleд\rangle$, i.e. the lowercase italic Cyrillic $\langleд\rangle$, may look like Latin $\langleg\rangle$, and $\langleт\rangle$, i.e. lowercase italic Cyrillic $\langleт\rangle$, may look like small-capital italic $\langleT\rangle$.

In Standard Serbian, as well as in Macedonian, some italic and cursive letters are allowed to be different, to more closely resemble the handwritten letters. The regular (upright) shapes are generally standardized in small caps form.

Notes: Depending on fonts available, the Serbian row may appear identical to the Russian row. Unicode approximations are used in the faux row to ensure it can be rendered properly across all systems.

In the Bulgarian alphabet, many lowercase letterforms may more closely resemble the cursive forms on the one hand and Latin glyphs on the other hand, e.g. by having an ascender or descender or by using rounded arcs instead of sharp corners. Sometimes, uppercase letters may have a different shape as well, e.g. more triangular, Д and Л, like Greek delta Δ and lambda Λ.

Notes: Depending on fonts available, the Bulgarian row may appear identical to the Russian row. Unicode approximations are used in the faux row to ensure it can be rendered properly across all systems; in some cases, such as ж with k-like ascender, no such approximation exists.

Accessing variant forms
Computer fonts typically default to the Central/Eastern, Russian letterforms, and require the use of OpenType Layout (OTL) features to display the Western, Bulgarian or Southern, Serbian/Macedonian forms. Depending on the choices made by the (computer) font designer, they may either be automatically activated by the local variant  feature for text tagged with an appropriate language code, or the author needs to opt-in by activating a stylistic set   or character variant   feature. These solutions only enjoy partial support and may render with default glyphs in certain software configurations, and the reader may not see the same result as the author intended.

Cyrillic alphabets
Among others, Cyrillic is the standard script for writing the following languages:

Slavic languages:

 * Belarusian
 * Bulgarian
 * Macedonian
 * Russian

 * Rusyn
 * Serbo-Croatian (Standard Serbian and Montenegrin)
 * Ukrainian

Non-Slavic languages of Russia:

 * Abaza
 * Adyghe
 * Avar
 * Azerbaijani (in Dagestan)
 * Bashkir
 * Buryat
 * Chechen
 * Chuvash
 * Erzya
 * Ingush
 * Kabardian
 * Kalmyk
 * Karachay-Balkar

 * Kildin Sami
 * Komi
 * Mari
 * Moksha
 * Nogai
 * Ossetian (in North Ossetia–Alania)
 * Romani
 * Sakha/Yakut
 * Tatar
 * Tuvan
 * Udmurt
 * Yuit (Yupik)

Non-Slavic languages in other countries:

 * Abkhaz
 * Aleut (now mostly in church texts)
 * Dungan
 * Kazakh (to be replaced by Latin script by 2025 ),
 * Kyrgyz

 * Mongolian (to also be written with traditional Mongolian script by 2025 )
 * Tajik
 * Tlingit (now only in church texts)
 * Turkmen (officially replaced by Latin script)
 * Uzbek (also officially replaced by Latin script, but still in wide use)
 * Yupik (in Alaska)

The Cyrillic script has also been used for languages of Alaska, Slavic Europe (except for Western Slavic and some Southern Slavic), the Caucasus, the languages of Idel-Ural, Siberia, and the Russian Far East.

The first alphabet derived from Cyrillic was Abur, used for the Komi language. Other Cyrillic alphabets include the Molodtsov alphabet for the Komi language and various alphabets for Caucasian languages.

Latin script
A number of languages written in a Cyrillic alphabet have also been written in a Latin alphabet, such as Azerbaijani, Uzbek, Serbian, and Romanian (in the Republic of Moldova until 1989 and in the Danubian Principalities throughout the 19th century). After the disintegration of the Soviet Union in 1991, some of the former republics officially shifted from Cyrillic to Latin. The transition is complete in most of Moldova (except the breakaway region of Transnistria, where Moldovan Cyrillic is official), Turkmenistan, and Azerbaijan. Uzbekistan still uses both systems, and Kazakhstan has officially begun a transition from Cyrillic to Latin (scheduled to be complete by 2025). The Russian government has mandated that Cyrillic must be used for all public communications in all federal subjects of Russia, to promote closer ties across the federation. This act was controversial for speakers of many Slavic languages; for others, such as Chechen and Ingush speakers, the law had political ramifications. For example, the separatist Chechen government mandated a Latin script which is still used by many Chechens.

Standard Serbian uses both the Cyrillic and Latin scripts. Cyrillic is nominally the official script of Serbia's administration according to the Serbian constitution; however, the law does not regulate scripts in standard language, or standard language itself by any means. In practice the scripts are equal, with Latin being used more often in a less official capacity.

The Zhuang alphabet, used between the 1950s and 1980s in portions of the People's Republic of China, used a mixture of Latin, phonetic, numeral-based, and Cyrillic letters. The non-Latin letters, including Cyrillic, were removed from the alphabet in 1982 and replaced with Latin letters that closely resembled the letters they replaced.

Romanization
There are various systems for romanization of Cyrillic text, including transliteration to convey Cyrillic spelling in Latin letters, and transcription to convey pronunciation.

Standard Cyrillic-to-Latin transliteration systems include:
 * Scientific transliteration, used in linguistics, is based on the Serbo-Croatian Latin alphabet.
 * The Working Group on Romanization Systems of the United Nations recommends different systems for specific languages. These are the most commonly used around the world.
 * ISO 9:1995, from the International Organization for Standardization.
 * American Library Association and Library of Congress Romanization tables for Slavic alphabets (ALA-LC Romanization), used in North American libraries.
 * BGN/PCGN Romanization (1947), United States Board on Geographic Names & Permanent Committee on Geographical Names for British Official Use).
 * GOST 16876, a now defunct Soviet transliteration standard. Replaced by GOST 7.79-2000, which is based on ISO 9.
 * Various informal romanizations of Cyrillic, which adapt the Cyrillic script to Latin and sometimes Greek glyphs for compatibility with small character sets.

See also Romanization of Belarusian, Bulgarian, Kyrgyz, Russian, Macedonian and Ukrainian.

Cyrillization
Representing other writing systems with Cyrillic letters is called Cyrillization.

Summary table

 * Ё in Russian is usually spelled as Е; Ё is typically printed in texts for learners and in dictionaries, and in word pairs which are differentiated only by that letter (все – всё).

Unicode
As of Unicode version, Cyrillic letters, including national and historical alphabets, are encoded across several blocks:
 * Cyrillic: U+0400–U+04FF
 * Cyrillic Supplement: U+0500–U+052F
 * Cyrillic Extended-A: U+2DE0–U+2DFF
 * Cyrillic Extended-B: U+A640–U+A69F
 * Cyrillic Extended-C: U+1C80–U+1C8F
 * Cyrillic Extended-D: U+1E030–U+1E08F
 * Phonetic Extensions: U+1D2B, U+1D78
 * Combining Half Marks: U+FE2E–U+FE2F

The characters in the range U+0400 to U+045F are essentially the characters from ISO 8859-5 moved upward by 864 positions. The characters in the range U+0460 to U+0489 are historic letters, not used now. The characters in the range U+048A to U+052F are additional letters for various languages that are written with Cyrillic script.

Unicode as a general rule does not include accented Cyrillic letters. A few exceptions include:
 * combinations that are considered as separate letters of respective alphabets, like Й, Ў, Ё, Ї, Ѓ, Ќ (as well as many letters of non-Slavic alphabets);
 * two most frequent combinations orthographically required to distinguish homonyms in Bulgarian and Macedonian: Ѐ, Ѝ;
 * a few Old and New Church Slavonic combinations: Ѷ, Ѿ, Ѽ.

To indicate stressed or long vowels, combining diacritical marks can be used after the respective letter (for example, : е́ у́ э́ etc.).

Some languages, including Church Slavonic, are still not fully supported.

Unicode 5.1, released on 4 April 2008, introduces major changes to the Cyrillic blocks. Revisions to the existing Cyrillic blocks, and the addition of Cyrillic Extended A (2DE0 ... 2DFF) and Cyrillic Extended B (A640 ... A69F), significantly improve support for the early Cyrillic alphabet, Abkhaz, Aleut, Chuvash, Kurdish, and Moksha.

Other
Other character encoding systems for Cyrillic:
 * CP866 – 8-bit Cyrillic character encoding established by Microsoft for use in MS-DOS also known as GOST-alternative. Cyrillic characters go in their native order, with a "window" for pseudographic characters.
 * ISO/IEC 8859-5 – 8-bit Cyrillic character encoding established by International Organization for Standardization
 * KOI8-R – 8-bit native Russian character encoding. Invented in the USSR for use on Soviet clones of American IBM and DEC computers. The Cyrillic characters go in the order of their Latin counterparts, which allowed the text to remain readable after transmission via a 7-bit line that removed the most significant bit from each byte – the result became a very rough, but readable, Latin transliteration of Cyrillic. Standard encoding of early 1990s for Unix systems and the first Russian Internet encoding.
 * KOI8-U – KOI8-R with addition of Ukrainian letters.
 * MIK – 8-bit native Bulgarian character encoding for use in Microsoft DOS.
 * Windows-1251 – 8-bit Cyrillic character encoding established by Microsoft for use in Microsoft Windows. The simplest 8-bit Cyrillic encoding – 32 capital chars in native order at 0xc0–0xdf, 32 usual chars at 0xe0–0xff, with rarely used "YO" characters somewhere else. No pseudographics. Former standard encoding in some Linux distributions for Belarusian and Bulgarian, but currently displaced by UTF-8.
 * GOST-main.
 * GB 2312 – Principally simplified Chinese encodings, but there are also the basic 33 Russian Cyrillic letters (in upper- and lower-case).
 * JIS and Shift JIS – Principally Japanese encodings, but there are also the basic 33 Russian Cyrillic letters (in upper- and lower-case).

Keyboard layouts
Each language has its own standard keyboard layout, adopted from traditional national typewriters. With the flexibility of computer input methods, there are also transliterating or phonetic/homophonic keyboard layouts made for typists who are more familiar with other layouts, like the common English QWERTY keyboard. When practical Cyrillic keyboard layouts are unavailable, computer users sometimes use transliteration (translit) or look-alike (volapuk encoding) to type in languages that are normally written with the Cyrillic alphabet. Potentially, these proxy versions could be transformed programmatically into Cyrillic at a later date.

Internet top-level domains in Cyrillic

 * gTLDs
 * .мон
 * .бг
 * .қаз
 * .рф
 * .срб
 * .укр
 * .мкд
 * .бел

title: Cyrillic script


text:
Consonant

In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract, except for the h, which is pronounced without any stricture in the vocal tract. Examples are and [b], pronounced with the lips;  and [d], pronounced with the front of the tongue;  and [g], pronounced with the back of the tongue;, pronounced throughout the vocal tract; , [v], and , pronounced by forcing air through a narrow channel (fricatives); and  and , which have air flowing through the nose (nasals). Most consonants are pulmonic, using air pressure from the lungs to generate a sound. Very few natural languages are non-pulmonic, making use of ejectives, implosives, and clicks. Contrasting with consonants are vowels.

Since the number of speech sounds in the world's languages is much greater than the number of letters in any one alphabet, linguists have devised systems such as the International Phonetic Alphabet (IPA) to assign a unique and unambiguous symbol to each attested consonant. The English alphabet has fewer consonant letters than the English language has consonant sounds, so digraphs like $⟨ch⟩$, $\langlesh\rangle$, $\langleth\rangle$, and $\langleng\rangle$ are used to extend the alphabet, though some letters and digraphs represent more than one consonant. For example, the sound spelled $\langleth\rangle$ in "this" is a different consonant from the $\langleth\rangle$ sound in "thin". (In the IPA, these are and, respectively.)

Etymology
The word consonant comes from Latin oblique stem cōnsonant-, from cōnsonāns 'sounding-together', a calque of Greek σύμφωνον sýmphōnon (plural sýmphōna, σύμφωνα).

Dionysius Thrax calls consonants sýmphōna (σύμφωνα 'sounded with') because in Greek they can only be pronounced with a vowel. He divides them into two subcategories: hēmíphōna (ἡμίφωνα 'half-sounded'), which are the continuants, and áphōna (ἄφωνος 'unsounded'), which correspond to plosives.

This description does not apply to some languages, such as the Salishan languages, in which plosives may occur without vowels (see Nuxalk), and the modern concept of "consonant" does not require co-occurrence with a vowel.

Consonant sounds and consonant letters
The word consonant may be used ambiguously for both speech sounds and the letters of the alphabet used to write them. In English, these letters are B, C, D, F, G, J, K, L, M, N, P, Q, S, T, V, X, Z and often H, R, W, Y.

In English orthography, the letters H, R, W, Y and the digraph GH are used for both consonants and vowels. For instance, the letter Y stands for the consonant/semi-vowel in yoke, the vowel  in myth, the vowel  in funny, the diphthong  in sky, and forms several digraphs for other diphthongs, such as say, boy, key. Similarly, R commonly indicates or modifies a vowel in non-rhotic accents.

This article is concerned with consonant sounds, however they are written.

Consonants versus vowels
Consonants and vowels correspond to distinct parts of a syllable: The most sonorous part of the syllable (that is, the part that is easiest to sing), called the syllabic peak or nucleus, is typically a vowel, while the less sonorous margins (called the onset and coda) are typically consonants. Such syllables may be abbreviated CV, V, and CVC, where C stands for consonant and V stands for vowel. This can be argued to be the only pattern found in most of the world's languages, and perhaps the primary pattern in all of them. However, the distinction between consonant and vowel is not always clear cut: there are syllabic consonants and non-syllabic vowels in many of the world's languages.

One blurry area is in segments variously called semivowels, semiconsonants, or glides. On one side, there are vowel-like segments that are not in themselves syllabic, but form diphthongs as part of the syllable nucleus, as the i in English boil. On the other, there are approximants that behave like consonants in forming onsets, but are articulated very much like vowels, as the y in English yes. Some phonologists model these as both being the underlying vowel, so that the English word bit would phonemically be , beet would be , and yield would be phonemically. Likewise, foot would be, food would be , wood would be , and wooed would be. However, there is a (perhaps allophonic) difference in articulation between these segments, with the in  yes and  yield and the  of  wooed having more constriction and a more definite place of articulation than the  in  boil or  bit or the  of  foot.

The other problematic area is that of syllabic consonants, segments articulated as consonants but occupying the nucleus of a syllable. This may be the case for words such as church in rhotic dialects of English, although phoneticians differ in whether they consider this to be a syllabic consonant,, or a rhotic vowel, : Some distinguish an approximant that corresponds to a vowel , for rural as  or ; others see these as a single phoneme,.

Other languages use fricative and often trilled segments as syllabic nuclei, as in Czech and several languages in Democratic Republic of the Congo, and China, including Mandarin Chinese. In Mandarin, they are historically allophones of, and spelled that way in Pinyin. Ladefoged and Maddieson call these "fricative vowels" and say that "they can usually be thought of as syllabic fricatives that are allophones of vowels". That is, phonetically they are consonants, but phonemically they behave as vowels.

Many Slavic languages allow the trill and the lateral  as syllabic nuclei (see Words without vowels). In languages like Nuxalk, it is difficult to know what the nucleus of a syllable is, or if all syllables even have nuclei. If the concept of 'syllable' applies in Nuxalk, there are syllabic consonants in words like (?) 'seal fat'. Miyako in Japan is similar, with 'to build' and  'to pull'.

Each spoken consonant can be distinguished by several phonetic features:

 * The manner of articulation is how air escapes from the vocal tract when the consonant or approximant (vowel-like) sound is made. Manners include stops, fricatives, and nasals.

 * The place of articulation is where in the vocal tract the obstruction of the consonant occurs, and which speech organs are involved. Places include bilabial (both lips), alveolar (tongue against the gum ridge), and velar (tongue against soft palate). In addition, there may be a simultaneous narrowing at another place of articulation, such as palatalisation or pharyngealisation. Consonants with two simultaneous places of articulation are said to be coarticulated.

 * The phonation of a consonant is how the vocal cords vibrate during the articulation. When the vocal cords vibrate fully, the consonant is called voiced; when they do not vibrate at all, it is voiceless.

 * The voice onset time (VOT) indicates the timing of the phonation. Aspiration is a feature of VOT.

 * The airstream mechanism is how the air moving through the vocal tract is powered. Most languages have exclusively pulmonic egressive consonants, which use the lungs and diaphragm, but ejectives, clicks, and implosives use different mechanisms.

 * The length is how long the obstruction of a consonant lasts. This feature is borderline distinctive in English, as in "wholly" vs. "holy", but cases are limited to morpheme boundaries. Unrelated roots are differentiated in various languages such as Italian, Japanese, and Finnish, with two length levels, "single" and "geminate". Estonian and some Sami languages have three phonemic lengths: short, geminate, and long geminate, although the distinction between the geminate and overlong geminate includes suprasegmental features.

 * The articulatory force is how much muscular energy is involved. This has been proposed many times, but no distinction relying exclusively on force has ever been demonstrated.

All English consonants can be classified by a combination of these features, such as "voiceless alveolar stop". In this case, the airstream mechanism is omitted.

Some pairs of consonants like p::b, t::d are sometimes called fortis and lenis, but this is a phonological rather than phonetic distinction.

Consonants are scheduled by their features in a number of IPA charts:

Examples
The recently extinct Ubykh language had only 2 or 3 vowels but 84 consonants; the Taa language has 87 consonants under one analysis, 164 under another, plus some 30 vowels and tone. The types of consonants used in various languages are by no means universal. For instance, nearly all Australian languages lack fricatives; a large percentage of the world's languages lack voiced stops such as, , as phonemes, though they may appear phonetically. Most languages, however, do include one or more fricatives, with being the most common, and a liquid consonant or two, with  the most common. The approximant is also widespread, and virtually all languages have one or more nasals, though a very few, such as the Central dialect of Rotokas, lack even these. This last language has the smallest number of consonants in the world, with just six.

Most common
In rhotic American English, the consonants spoken most frequently are. ( is less common in non-rhotic accents.) The most frequent consonant in many other languages is.

The most universal consonants around the world (that is, the ones appearing in nearly all languages) are the three voiceless stops, , , and the two nasals ,. However, even these common five are not completely universal. Several languages in the vicinity of the Sahara Desert, including Arabic, lack. Several languages of North America, such as Mohawk, lack both of the labials and. The Wichita language of Oklahoma and some West African languages, such as Ijo, lack the consonant on a phonemic level, but do use it phonetically, as an allophone of another consonant (of  in the case of Ijo, and of  in Wichita). A few languages on Bougainville Island and around Puget Sound, such as Makah, lack both of the nasals and  altogether, except in special speech registers such as baby-talk. The 'click language' Nǁng lacks, and colloquial Samoan lacks both alveolars, and. Despite the 80-odd consonants of Ubykh, it lacks the plain velar in native words, as do the related Adyghe and Kabardian languages. But with a few striking exceptions, such as Xavante and Tahitian—which have no dorsal consonants whatsoever—nearly all other languages have at least one velar consonant: most of the few languages that do not have a simple (that is, a sound that is generally pronounced ) have a consonant that is very similar. For instance, an areal feature of the Pacific Northwest coast is that historical *k has become palatalized in many languages, so that Saanich for example has and  but no plain ;  similarly, historical *k in the Northwest Caucasian languages became palatalized to  in extinct Ubykh and to  in most Circassian dialects.

title: Consonant


text:
Costume jewelry

Costume or fashion jewelry includes a range of decorative items worn for personal adornment that are manufactured as less expensive ornamentation to complement a particular fashionable outfit or garment as opposed to "real" (fine) jewelry, which is more costly and which may be regarded primarily as collectibles, keepsakes, or investments. From the outset, costume jewelry — also known as fashion jewelry — paralleled the styles of its more precious fine counterparts.

Terminology
It is also known as artificial jewellery, imitation jewellery, imitated jewelry, trinkets, fashion jewelry, junk jewelry, fake jewelry, or fallalery.

Etymology
The term costume jewelry dates back to the early 20th century. It reflects the use of the word "costume" to refer to what is now called an "outfit".

Components
Originally, costume or fashion jewelry was made of inexpensive simulated gemstones, such as rhinestones or lucite, set in pewter, silver, nickel, or brass. During the depression years, rhinestones were even down-graded by some manufacturers to meet the cost of production.

During the World War II era, sterling silver was often incorporated into costume jewelry designs primarily because: This resulted in a number of years during which sterling silver costume jewelry was produced and some can still be found in today's vintage jewelry marketplace.
 * 1) The components used for base metal were needed for wartime production (i.e., military applications), and a ban was placed on their use in the private sector.
 * 2) Base metal was originally popular because it could approximate platinum's color, sterling silver fulfilled the same function.

Modern costume jewelry incorporates a wide range of materials. High-end crystals, cubic zirconia simulated diamonds, and some semi-precious stones are used in place of precious stones. Metals include gold- or silver-plated brass, and sometimes vermeil or sterling silver. Lower-priced jewelry may still use gold plating over pewter, nickel, or other metals; items made in countries outside the United States may contain lead. Some pieces incorporate plastic, acrylic, leather, or wood.

Historical expression
Costume jewelry can be characterized by the period in history in which it was made.

Art Deco period (1920–1930s)
The Art Deco movement was an attempt to combine the harshness of mass production with the sensitivity of art and design. The movement died with the onset of the Great Depression and the outbreak of World War II.

According to Schiffer, some of the characteristics of the costume jewelry in the Art Deco period were:
 * Free-flowing curves were replaced with a harshly geometric and symmetrical theme
 * Long pendants, bangle bracelets, cocktail rings, and elaborate accessory items such as cigarette cases and holders

Retro period (1935 to 1950)
In the Retro period, designers struggled with the art versus mass production dilemma. Natural materials merged with plastics. The retro period primarily included American-made jewelry, which had a distinctly American look. With the war in Europe, many European jewelry firms were forced to shut down. Many European designers emigrated to the U.S. since the economy was recovering.

According to Schiffer, some of the characteristics of costume jewelry in the Retro period were:
 * Glamour, elegance, and sophistication
 * Flowers, bows, and sunburst designs with a Hollywood flair
 * Moonstones, horse motifs, military influence, and ballerinas
 * Bakelite and other plastic jewelry

Art Modern period (1945 to 1960)
In the Art Modern period following World War II, jewelry designs became more traditional and understated. The big, bold styles of the Retro period went out of style and were replaced by the more tailored styles of the 1950s and 1960s.

According to Schiffer, some of the characteristics of costume jewelry in the Art Modern period were:
 * Bold, lavish jewelry
 * Large, chunky bracelets, charm bracelets, Jade/opal, citrine and topaz
 * Poodle pins, Christmas tree pins, and other Christmas jewelry
 * Rhinestones

With the advent of the Mod period came "Body Jewelry". Carl Schimel of Kim Craftsmen Jewelry was at the forefront of this style. While Kim Craftsmen closed in the early 1990s, many collectors still forage for their items at antique shows and flea markets.

General history
Costume jewelry has been part of the culture for almost 300 years. During the 18th century, jewelers began making pieces with inexpensive glass. In the 19th century, costume jewelry made of semi-precious material came into the market. Jewels made of semi-precious material were more affordable, and this affordability gave common people the chance to own costume jewelry.

But the real golden era for costume jewelry began in the middle of the 20th century. The new middle class wanted beautiful, but affordable jewelry. The demand for jewelry of this type coincided with the machine age and the industrial revolution. The revolution made the production of carefully executed replicas of admired heirloom pieces possible.

As the class structure in America changed, so did measures of real wealth. Women in all social stations, even the working-class woman, could own a small piece of costume jewelry. The average town and countrywoman could acquire and wear a considerable amount of this mass-produced jewelry that was both affordable and stylish.

Costume jewelry was also made popular by various designers in the mid-20th century. Some of the most remembered names in costume jewelry include both the high and low priced brands: Crown Trifari, Dior, Chanel, Miriam Haskell, Sherman, Monet, Napier, Corocraft, Coventry, and Kim Craftsmen.

A significant factor in the popularization of costume jewelry was Hollywood movies. The leading female stars of the 1940s and 1950s often wore and then endorsed the pieces produced by a range of designers. If you admired a necklace worn by Bette Davis in The Private Lives of Elizabeth and Essex, you could buy a copy from Joseff of Hollywood, who made the original. Stars such as Vivien Leigh, Elizabeth Taylor, and Jane Russell appeared in adverts for the pieces and the availability of the collections in shops such as Woolworth made it possible for ordinary women to own and wear such jewelry.

Coco Chanel greatly popularized the use of faux jewelry in her years as a fashion designer, bringing costume jewelry to life with gold and faux pearls. Kenneth Jay Lane has since the 1960s been known for creating unique pieces for Jackie Onassis, Elizabeth Taylor, Diana Vreeland, and Audrey Hepburn. He is probably best known for his three-strand faux pearl necklace worn by Barbara Bush to her husband's inaugural ball.

In many instances, high-end fashion jewelry has achieved a "collectible" status and increased value over time. Today, there is a substantial secondary market for vintage fashion jewelry. The main collecting market is for 'signed pieces', that is pieces that have the maker's mark, usually stamped on the reverse. Amongst the most sought after are Miriam Haskell, Sherman, Coro, Butler and Wilson, Crown Trifari, and Sphinx. However, there is also demand for good quality 'unsigned' pieces, especially if they are of an unusual design.

Business and industry
Costume jewelry is considered a discrete category of fashion accessory and displays many characteristics of a self-contained industry. Costume jewelry manufacturers are located throughout the world, with a particular concentration in parts of China and India, where entire citywide and region-wide economies are dominated by the trade of these goods. There has been considerable controversy in the United States and elsewhere about the lack of regulations in the manufacture of such jewelry—these range from human rights issues surrounding the treatment of labor, to the use of manufacturing processes in which small, but potentially harmful, amounts of toxic metals are added during production. In 2010, the Associated Press released the story that toxic levels of the metal cadmium were found in children's jewelry. An Associated Press investigation found some pieces contained more than 80 percent of cadmium. The wider issues surrounding imports, exports, trade laws, and globalization also apply to the costume jewelry trade.

As part of the supply chain, wholesalers in the United States and other nations purchase costume jewelry from manufacturers and typically import or export it to wholesale distributors and suppliers who deal directly with retailers. Wholesale costume jewelry merchants will traditionally seek out new suppliers at trade shows. As the Internet has become increasingly important in global trade, the trade-show model has changed. Retailers can now select from a large number of wholesalers with sites on the World Wide Web. The wholesalers purchase from international suppliers who are also available on the Web from different parts of the world like Chinese, Korean, Indonesian, Thai, and Indian jewelry companies, with their wide range of products in bulk quantities. Some of these sites also market directly to consumers who can purchase costume jewelry at greatly reduced prices. Some of these websites categorize fashion jewelry separately, while others use this term in place of costume jewelry. The trend of jewelry-making at home by hobbyists for personal enjoyment or for sale on sites like Etsy has resulted in the common practice of buying wholesale costume jewelry in bulk and using it for parts.

There is a rise in demand for artificial or imitation jewelry by 85% due to the increase in gold prices, according to a 2011 report.

title: Costume jewelry