Cattle

Many oxen are still in use worldwide, especially in developing nations. In addition, diamonds are the subject of various myths and legends. Though not as fast as horses, they are less prone to injury because they are more sure-footed and do not try to jerk the load. Clarke's 2061: Odyssey Three (1988) and Neal Stephenson's The Diamond Age (1995). This is one of the reasons that teams were dragging logs from forests long after horses had taken over most other draught uses in Europe and the New World. Notable pieces of fiction include Ian Fleming's Diamonds Are Forever (1956), Arthur C. Oxen can pull harder and longer than horses, particularly on obstinate or almost un-movable loads. Diamonds are a common focus of fiction.

Ox teams are steered by commands or noise (whip cracks) and many teamsters were known for their voices and language. The diamond is the birthstone for people born in the month of April, and is also used as the symbol of a sixty-year anniversary, such as a Diamond Jubilee (see hierarchy of precious substances). Their teamster must make or buy as many as a dozen yokes of different sizes as the animals grow. However, many people feel very uncomfortable at the thought of wearing the carbonized remains of people as jewelry. Oxen must be painstakingly trained from a young age. The LifeGem company further taps modern symbolism by offering to synthetically convert the carbonized remains of people or pets into "memorial diamonds". Yoked oxen cannot slow a load like harnessed horses can, the load has to be controlled downhill by other means. The Mattachine Society, one of the first and the foremost gay rights groups in the United States, used so-called harlequin diamonds (four smaller diamonds arranged in a pattern to form one larger diamond) as their emblem.

Oxen are chosen, from calves, with horns since the horns hold the yoke in place when the oxen lower their heads, back up or slow down (particularly with a wheeled vehicle going downhill). Diamonds were also a symbol of gay community in the 1950s. A wooden yoke is fastened about the neck of each pair so that the force of draft is distributed across their shoulders. Inaccessibility of diamonds to the vast majority of the population limited the popularity of diamonds as betrothal jewels during this period. In past days some teams were about fourteen, and even over twenty for logging. 1430–40), a pictorial piece depicting a wedding couple. Oxen are most often used in teams of two, paired, for light work such as carting. 1370–80) and the Heftlein brooch of Vienna (ca.

Also, the gait of the ox is often important to ox trainers, since the speed the animal walks should roughly match the gait of the ox driver who must work with it. Other early examples of betrothal jewels incorporating diamonds include the Bridal Crown of Blanche (ca. American ox trainers favored larger breeds for their ability to do more work in addition to their intelligence (the ability to learn); for the same reason, the typical ox is the male of a breed, rather than the smaller female. It can be traced to the marriage of Maximilian I (then Archduke of Austria) to Mary of Burgundy in 1477. The education consists of the animal's learning to respond appropriately to the teamster's (ox driver's) commands: in North America such as (1) get up, (2) whoa, (3) back up, (4) gee (turn to the right) and (5) haw (turn to the left). The diamond engagement ring is, however, not an original invention of De Beers. An ox is nothing more than a mature bovine with an "education". The popularity of this modern tradition can be traced directly to the marketing campaigns of De Beers, starting in 1938.

Contrary to popular American lore, an "ox" is not a unique breed of bovine, nor have any "blue" oxen lived outside the folk tales surrounding Paul Bunyan, the mythical American logger. Today, diamonds are used to symbolize eternity and love, being often seen adorning engagement rings and sometimes wedding rings as well. Oxen were commonly used to skid logs, and sometimes are still in low-impact select-cut logging, in forests. In Western culture, diamonds are the traditional emblem of fearlessness and virtue, but have also often associated with power, wealth, crime and misfortune. Oxen are used for plowing, transport, hauling cargo, grain-grinding by trampling or by powering machines, irrigation by powering pumps, and wagon drawing. In Tibetan Buddhism, also known as Vajrayana (Diamond Vehicle), diamonds are an important symbol, and the Diamond Sutra is one of the most popular texts. Usually an ox is over four years old due to the need for training and for time to grow to full size. Many long dead cultures have sought to explain diamond's superlative properties through divine or mystical affiliations.

Often they are adult, castrated males. It is said the Greeks believed diamonds were tears of the gods; the Romans believed they were splinters of fallen stars. Oxen (plural of ox) are cattle trained as draft animals. The point at which diamonds began to be associated with divinity is not known, but early texts indicate that it was recognized in India since at least 400 BCE. The outbreaks of mad cow disease have reduced or prevented some traditional uses of cattle for food, for example the eating of brains or spinal cords. The diamonds themselves were thought to be endowments from the gods and were therefore cherished. Other sports like Bull riding are seen as part of a Rodeo, especially in North America. Perhaps the earliest symbolic use of diamonds was as the eyes of Hindu devotional statues.

In Portugal, Spain and some Latin American countries, bulls are used in the sport of bullfighting while a similar sport Jallikattu is seen in South India; in many other countries this is illegal. Because of their extraordinary physical properties, diamonds have been used symbolically since near the time of their first discovery. In Latin America, Australia and the western North America cattle are grazed on large tracts of rangeland called ranchos, ranches or Stations (Australia). However, synthetic diamonds may one day be indistinguishable from natural diamonds, and new techniques for simulants (such as coating them with a very thin diamond-like layer of carbon) are making it harder to easily distinguish between simulants and real diamonds. It is common to see loose cattle walking the streets, because the holiness it holds in India and other countries that practice Hinduism. The established natural diamond industry has a vested interest in maintaining the distinction between natural diamonds and other diamonds, and has made significant investments toward that end. In fact a divine cow named Kamadhenu is considered to be the mother of all Hindu Gods. Currently, trained gemologists with appropriate equipment are able to distinguish natural diamonds from all synthetic and simulant diamonds, and identify all enhanced natural diamonds.

[2] The importance of the cow is highlighted by the fact that a regional holiday called Mattu Pongal (literally Cow Pongal in Tamil) exists which is akin to a bovine thanksgiving day. These include laser drilling to remove inclusions, application of sealants to fill cracks, treatments to improve a white diamond's color grade, and treatments to give fancy color to a white diamond. The bull is my sire.". Diamond enhancements are specific treatments, performed on natural diamonds (usually those already cut and polished into a gem), which are designed to better the gemological characteristics of the stone in one or more ways. In Hinduism, the cow is said to be holy (and thus should not be eaten); "The cow is my mother. Both CZ and moissanite are synthetically produced for use as a diamond simulant. Their ability to provide meat, dairy and draft while reproducing themselves and eating nothing but grass has furthered human interests dramatically through the millennia. The most familiar diamond simulant to most consumers is cubic zirconia (commonly abbreviated as CZ); recently moissanite has also gained cachet as a popular diamond simulant.

Some consider them the oldest form of wealth. Materials which have similar gemological characteristics to diamond but are not real mined or synthetic diamond are known as diamond simulants. Cattle occupy a unique role in human history. A diamond's gem quality, which is not as dependent on material properties as industrial applications, has invited both imitation and the invention of procedures to enhance the gemological properties of natural diamonds. The red color is merely traditional, as the movement of the cape is the attractant. Diamonds have been manufactured synthetically for over fifty years. This rumour derives from bullfighting, where Matadors traditionally use red-coloured capes to provoke bulls into attacking. This process has historically produced industrial-grade diamonds, but synthetic diamond producers have recently begun to penetrate the gem diamond market.

This is incorrect, as cattle are mostly colour-blind. A portion of this demand is now being met by synthetic diamonds, man-made diamonds which have similar properties to natural diamonds. A popular misconception about cattle (primarily bulls) is that they are enraged by the colour red. The gemological and industrial uses of diamond have created a large demand for raw stones. Breeders have attempted to recreate the original gene pool of the aurochs by careful crossing of commercial breeds, creating the Heck cattle breed. [4]. In historical times, their range was restricted to Europe, and the last animals were killed by poachers in Masovia, Poland, in 1627. According to the Rio Tinto Group, in 2002 the diamonds produced and released to the market were valued at US$9 billion as rough diamonds, US$14 billion after being cut and polished, US$28 billion in wholesale diamond jewelry, and retail sales of US$57 billion.

The aurochs was originally spread throughout Europe, Africa, and Asia. Diamonds can be sold already set in jewelry, or as is increasingly popular, sold unset ("loose"). The omasum is known as the "Many Plies." The abomasum is most like the human stomach; this is why it is known as the "True Stomach.". This is the final tightly controlled step in the diamond supply chain; wholesalers and even retailers are able to buy relatively small lots of diamonds at the bourses, after which they are prepared for final sale to the consumer. The reticulum is known as the "Honeycomb." The omasum's main function is to absorb water and nutrients from the digestible feed. There are 24 registered diamond bourses. Cattle sometimes consume metal objects which are deposited in the reticulum, and this is where hardware disease occurs. Diamonds which have been prepared as gemstones are sold on diamond exchanges called bourses.

The rumen is the largest compartment and the reticulum is the smallest compartment. The recent expansion of this industry in India, employing low cost labor, has allowed smaller diamonds to be prepared as gems than was previously economically feasible. They are the rumen, reticulum, omasum, and abomasum. Demonstrating this, India produces 90% of all cut and polished diamonds by number, but only 55% by value. Cattle have one stomach, with four compartments. Cutting centers with lower costs of labor, notably Surat in Gujarat, India, handle a larger number of smaller carat diamonds, while smaller quantities of larger or more valuable diamonds are more likely to be handled in Europe or North America. These features allow them to thrive on grasses and other vegetation. Recently, diamond cutting centers have been established in China, India, and Thailand.

The microbes that live inside of the rumen are also able to synthesize amino acids from non-protein nitrogenous sources such as urea and ammonia. Traditional diamond cutting centers are Antwerp, Amsterdam, Johannesburg, New York, and Tel Aviv. These microbes are primarily responsible for generating the volatile fatty acids (VGAs) that cattle use as their primary metabolic fuel. The cutting and polishing of rough diamonds is a specialized skill that is concentrated in a limited number of locations worldwide. Cattle are ruminants, meaning that they have a unique digestive system that allows them to digest otherwise unpalatable foods by repeatedly regurgitating and rechewing them as "cud." The cud is then reswallowed and further digested by specialized bacterial, protozoal and fungal microbes that live in the rumen. Once purchased by sightholders, diamonds are cut and polished in preparation for sale as gemstones. The word "heifer" is sometimes used in a similar fashion, the implication being that the target of the term is overweight. DTC performs sophisticated sorting of rough diamonds into over 16,000 categories, and then sells bulk lots of rough diamonds to a limited number of sightholders a few times a year.

In some countries, such as the UK, this slur is used exclusively for women whereas in others it may be used for both genders. The Diamond Trading Company, or DTC, is a subsidiary of De Beers and markets rough diamonds produced both by De Beers mines and other mines from which it purchases rough diamond production; in whole, about two thirds of all rough diamonds pass through the company. The word "cow" can also be used derogatively, when describing a person, whom one expresses a dislike for. In 2003, this constituted total production of nearly US$9 billion in value. Cows of certain breeds that are kept for the milk they give are called dairy cows. Currently, gem production totals nearly 30 million carats (6,000 kg) of cut and polished stones annually, and over 100 million carats (20,000 kg) of diamonds are sold for industrial use each year. Within the beef cattle industry in parts of the United States, the older term beef (plural beeves) is still used to refer to an animal of either gender. Although the Kimberly Process has been somewhat successful in limiting the number of conflict diamonds entering the market, conflict diamonds smuggled to market continue to persist to some degree.

Cattle raised for human consumption are called beef cattle. The Kimberley Process provides documentation and certification of diamond exports from producing countries to ensure that the proceeds of sale are not being used to fund criminal or revolutionary activities. Obsolete terms for cattle include "neat" (horned oxen, from which "neatsfoot oil" is derived), "beef" (young ox) and "beefing" (young animal fit for slaughtering). In response to public concerns that their diamond purchases were contributing to war and human rights abuses in central Africa and west Africa, the diamond industry and diamond-trading nations introduced the Kimberley Process in 2002, which is aimed at ensuring that conflict diamonds do not become intermixed with the diamonds not controlled by such rebel groups. Some Australian, Canadian, New Zealand and Scottish farmers use the term "cattlebeast". Diamonds sold through this process are known as conflict diamonds or blood diamonds. To refer to a specific number of these animals without specifying their gender, it must be stated as (for example) "ten head of cattle.". In some of the more politically unstable central African and west African countries, revolutionary groups have taken control of diamond mines, using proceeds from diamond sales to finance their operations.

Today "cow" is probably the closest to being gender-neutral, although it is usually understood to mean female (females of other animals, such as whales or elephants, are also called cows). Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes. But "ox" is no longer used in this general sense, being restricted to the sense given above. There are also commercial deposits being actively mined in the Northwest Territories of Canada, Siberia (mostly in Yakutia territory, for example Mir pipe and Udachnaya pipe), Brazil, and in Northern and Western Australia. That this was once the standard name for domestic bovines is shown in placenames such as Oxford. Today, most commercially viable diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, Angola and Sierra Leone. Strictly speaking, the singular noun for the domestic bovine is ox: a bull is a male ox and a cow is a female ox. The first non-Indian diamond source was found in Brazil in 1725.

There is no singular equivalent in modern English to cattle other than the various gender and age-specific terms (though "catron" is occasionally seen as a half-serious proposal). Historically diamonds were known to be found only in alluvial deposits in southern India; India led the world in diamond production from the time of their discovery in approximately the 9th century BCE to the mid-18th century CE, but the commercial potential of these sources has been exhausted. Thus one may refer to some cattle, but not three cattle. The concentration of power only loosens at the retail level, where diamonds are sold by a limited number of distributors, known as sightholders, to jewelers around the world. The term cattle itself is not a plural, but a mass noun. In fact, the amount of power which De Beers has consolidated historically prevented it from direct trade with the United States, as its trade practices led to an indictment for violating antitrust regulations (the case was settled in 2004). The adjective applying to cattle is bovine. The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world.

An adult female over two years of age (approximately) is called a cow. See also: List of diamond mines. An intact male is called a bull. Significant research efforts in Japan, Europe, and the United States are under way to capitalize on the potential offered by diamond's unique material properties, combined with increased quality and quantity of supply starting to become available from synthetic diamond manufacturers. If castrated as an adult, it is called a stag. Garnering much excitement is the possible use of diamond as a semiconductor suitable to build microchips from, or the use of diamond as a heat sink in electronics. The castrated male is then called a bullock or steer, unless kept for draft purposes, in which case it is called an ox (plural oxen), not to be confused with the related wild musk ox. With the continuing advances being made in the production of synthetic diamond, future applications are beginning to become feasible.

Male cattle bred for meat are castrated unless needed for breeding. Specialized applications include use in laboratories as containment for high pressure experiments (see diamond anvil), high-performance bearings, and limited use in specialized windows. A young male is called a bull-calf; a young female before she has calved is called a heifer (pronounced "heffer"). Diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications. Young cattle are called calves. Most uses of diamonds in these technologies do not require large diamonds; in fact, most diamonds that are gem-quality except for their small size, can find an industrial use. This article refers to the common modern meaning of "cattle", the European domestic bovine. The dominant industrial use of diamond is in cutting, drilling, grinding, and polishing.

Additionally other species of the genus Bos are often called cattle or wild cattle. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 400 million carats (80,000 kg) of synthetic diamonds are produced annually for industrial use—nearly four times the mass of natural diamonds mined over the same period. Older English sources like King James Version of the Bible refer to livestock in general as cattle, or sometimes the archaic kine (which comes from the same English stem as cow). This helps explain why 80% of mined diamonds (equal to about 100 million carats or 20,000 kg annually), unsuitable for use as gemstones and known as bort, are destined for industrial use. The word is closely related to "chattel" (a unit of property) and to "capital" in the sense of "property.". Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamond, including clarity and color, mostly irrelevant. It derives from the Latin caput, head, and thus originally meant "unit of livestock" or "one head". The market for industrial-grade diamonds operates much differently from its gem-grade counterpart.

The word "cattle" did not originate as a name for bovine animals. This coordinated campaign has lasted decades and continues today; it is perhaps best captured by the now-familiar slogan "a diamond is forever". . Ayer's multifaceted marketing campaign included product placement, advertising the diamond itself rather than the De Beers brand, and building associations with celebrities and royalty. (See aurochs for the history of domestication, and zebu for peculiarities of that group.). N.W. Cattle cannot successfully be bred with water buffalo or African buffalo. Ayer & Son, the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market and opened up new markets, even in countries where no diamond tradition had existed before.

For example, genetic testing of the Dwarf Lulu breed, the only humpless "Bos taurus-type" cattle in Nepal, found them to be a mix of European cattle, zebu and yak. N.W. Hybrid individuals and even breeds exist, not only between European cattle and zebu but also with yaks, banteng, gaur, and bison, a cross-genera hybrid. The De Beers diamond advertising campaign is acknowledged as one of the most successful and innovative ones in history. Complicating the matter is the ability of cattle to interbreed with other closely related species. De Beers has used its monopoly position to establish strict price controls, and aggressively market diamonds directly to consumers in world markets. More recently these three have increasingly been grouped as one species, sometimes using the names Bos primigenius taurus, Bos primigenius indicus and Bos primigenius primigenius. At one time it was thought over 80 percent of the world's rough diamonds passed through the Diamond Trading Company (DTC, a subsidiary of De Beers) in London, but presently the figure is estimated at around 60 percent.

The aurochs is ancestral to both zebu and European cattle. The company and its subsidiaries own mines that produce some 40 percent of annual world diamond production, and control distribution channels handling nearly two thirds of all gem diamonds. These were Bos taurus, the European cattle, including similar types from Africa and Asia; Bos indicus, the zebu; and the extinct Bos primigenius, the aurochs. De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) and distribution channels for gem-quality diamonds. Cattle were originally identified by Carolus Linnaeus as three separate species. The De Beers company holds a clearly dominant position in the industry, and has done so since soon after its founding in 1888. It is estimated that there are 1.3 billion head of cattle in the world today [1]. The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers (the most important being Antwerp).

In some countries, such as India, they are subject to religious ceremonies and respect. They are based in Johannesburg, South Africa and London, England. They are raised as livestock for meat (called beef and veal), dairy products (milk), leather and as draught animals (pulling carts, plows and the like). One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and diamond cutting is limited to a few locations (most importantly New York, Antwerp, London, Tel Aviv, Amsterdam and Surat), and a single company—De Beers—controls over half of all trade in diamonds. Cattle (called cows in vernacular usage) are domesticated ungulates, a member of the subfamily Bovinae of the family Bovidae. Unlike precious metals such as gold or platinum, gem diamonds do not trade as a commodity: there is a substantial mark-up in the sale of diamonds, and there is not a very active market for resale of diamonds. The cow is a photograph that the animators manipulate in such a way as to suggest that the cow is performing all kinds of unusual feats when obviously, it is just a photograph being moved around. A large trade in gem-grade diamonds exists.

The Drawn Together episode "A Tale of Two Cows" features a character called Live Action Cow. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways. Later the cow is mangled and run over several times by a semi truck and some bikers while the man begs for Shiva's forgivness. The diamond industry can be broadly separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. In the movie Bubble Boy an Indian ice cream man is threatened by the Indian god Shiva because he accidentally ran over a cow. The largest flawless and colorless (grade D) diamond is the Millennium Star (1990) at 203.04 carats. The popular nursery rhyme 'Hey, diddle-diddle' features a cow jumping over the moon. One of the diamonds cut from it, Cullinan I or the Great Star of Africa, was formerly the largest cut diamond at 530.2 carats, but now that title has been taken by the Golden Jubilee (1985), a 545.67 carat yellow-brown diamond.

A Texas Longhorn with burnt orange coloring named Bevo is the mascot of the sports teams at the University of Texas at Austin. The Cullinan Diamond, owned by Queen Elizabeth II was the largest gem-quality rough diamond ever found (1905), at 3,106.75 carats. In Kung Pow: Enter the Fist, a famous scene parodying The Matrix bullet time scene involves a 3D animated cow being fought by the hero. A number of large diamonds have become historically significant objects, as their inclusion in various sets of crown jewels and the purchase, sale, and sometimes theft of notable diamonds, have sometimes become politicized. In the Computer Game Starcraft and Starcraft:Broodwar the cheat code "there is no cow level" will immediately take the player to the next level. Popularity continued to rise as new cuts were developed that enhanced the diamond's aesthetic appeal, and has largely continued unabated to this day; diamonds have proven popular with all classes in society as their cost has become within reach. In the Computer Game Diablo II there is an area called the "Secret Cow Level" in which players can gain experience more quickly than usual by fighting an army of bipedal cows. However, within a century diamonds were popular gems among the moneyed aristocratic and merchant classes, and by at latest 1477 had begun to be used in wedding rings.

In a Grape-Nuts television commercial and in the movie Kingpin with Woody Harrelson, in which he pretends to be Amish, there are scenes of men "milking" a bull, thinking it is a cow. In the 13th century, King Louis IX of France established a law that only the king could own diamonds. These cows will sometimes say "Moo, I say!". The rise in popularity of diamonds as gems seems to have paralleled increasing availability through European history. In the game Fallout and Fallout 2, cows mutate into Brahman. In 1919, Marcel Tolkowsky developed an ideal round brilliant cut design that has set the standard for comparison of modern gems; however, diamond cuts have continued to be refined. In the movie Twister, cows are flung about, mooing, by tornadoes. Over the following centuries, various diamond cuts were introduced which increasingly demonstrated the fire and brilliance that makes diamonds treasured today: the table cut, the briolette (around 1476), the rose cut (mid-16th century), and by the mid-17th century, the Mazarin, the first brilliant cut diamond design.

In Monty Python and the Holy Grail, the French shoot cows out of catapults. By 1375, a guild of diamond polishers had been established at Nuremberg. The sound a cow makes is often used to create comedic effect. During this time, the taboo against cutting diamonds into gem shapes, which was established over 1,000 years earlier in the traditions of India, ended allowing the development of diamond cutting technology to begin in earnest. Since 1995, advertisements for Chick-fil-A restaurants have featured cows encouraging people to "Eat Mor Chikin.". Around 1300, the flow of diamonds into Europe increased via Venice's trade network, with most flowing through the low country ports of Bruges, Antwerp, and Amsterdam. The lilac-colored "Milka Cow" is a well-known symbol of the Milka brand of chocolate. Until the late Middle Ages, diamonds were most prized in their natural octahedral state, perhaps with the crystal surfaces polished to increase luster and remove foreign material.

Gary Larson's famous comic strip The Far Side frequently included cows in humorous situations. In Europe, however, diamonds disappeared for almost 1,000 years following the rise of Christianity because of two effects: early Christians rejected diamonds because of their earlier use in amulets, and Arabic traders restricted the flow of trade between Europe and India. (Kane, 5). Archeological evidence from Yemen suggests that diamonds were used as drill tips as early as the 4th century BCE. It said that all cattle and pigs have to have a registered brand or earmark by May 1, 1644. In China, diamonds seem to have been used primarily for engraving jade and drilling holes in beads. The first known law requiring branding in North America was enacted on February 5, 1644 by Connecticut. The Roman writer Pliny the Elder noted diamond's ornamental uses, as well as its usefulness to engravers because of its hardness, in his work Naturalis Historia.

The joke is apparent to anyone knowing that a cow possesses no such teeth. Diamonds were traded to both the east and west of India and were recognized by various cultures for their gemological or industrial uses. A humourous anecdote among farmers suggests that instant death will come to anyone bitten by a cattle's upper front teeth. At that scale, the surface of the modern diamond-polished corundum closely resembled that of the axes; however, the polishes of the latter were superior. On February 18, 1930 Elm Farm Ollie became the first cow to fly in an airplane and also the first cow to be milked in an airplane. Although there are diamond deposits now known to exist close to the burial sites, no direct evidence of coeval diamond mining has been found: the researchers came to this conclusion by polishing corundum using various lapidary abrasives and modern techniques then comparing the results using an atomic force microscope. Bulls in particular are seen as a symbolic emblem of duty and religion. team of archaeologists reported the discovery of four corundum-rich stone ceremonial burial axes originating from China's Liangzhu and Sanxingcun cultures (4000 BCE–2500 BCE) which, because of the axes' specular surfaces, the scientists believe were polished using diamond powder [2] [3].

They appear in numerous stories from the Purana's and Veda's, for example the deity Sri Krishna takes birth in a family of cowherders and Lord Shiva is said to ride on the back of a Bull. In February 2005, a joint Chinese-U.S. Cows are venerated within the Hindu religion of India: According to Vedic scripture they are to be treated with the same respect 'as one's mother' because of the milk they provide. Ownership was restricted among various castes by color, with only kings being allowed to own all colors of diamond. In the popular kids show The Fairly Odd Parents A cow tips over a kerosene lamp and the town mascott, a goat named "Chompy", saves the day by pushing the cow on to the fire, hence putting it out. Diamonds quickly became associated with divinity, being used to decorate religious icons, and were believed to bring good fortune to those who carried them. Michael Ahern, the reporter who created the cow story, admitted in 1893 that he had made it up because he thought it would make colorful copy. The earliest written reference can be found in the Sanskrit text Arthasastra, which was completed around 296 BCE, describes diamond's hardness, luster, and dispersion.

An apocryphal story has it that a cow started the Great Chicago Fire by kicking over a kerosene lamp. Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could then be found. The constellation Taurus represents a bull. However, cleanliness might reflect a diamond's sentimental value: some jewelers have noted a correlation between ring cleanliness and marriage quality [1]. See: Ox (Zodiac). Cleanliness does not affect the diamond's market value, as any competent jeweler will clean the diamond before offering it for sale. The ox is one of the 12-year cycle of animals which appear in the Chinese zodiac related to the Chinese calendar. Some jewelers provide their customers with ammonia-based cleaning kits; ultrasonic cleaners are also popular.

For the mythology and lore connected with the bull, see Bull (mythology). Maintaining a clean diamond can sometimes be difficult, as jewelry settings can obstruct cleaning efforts, and oils, grease, and other hydrophobic materials adhere well to a diamond's surface. Current practice is to thoroughly clean a diamond before grading its color. Historically, some jewelers' stones were misgraded because of smudges on the girdle, or dye on the culet. Colored dye or smudges can affect the perceived color of a diamond.

Even a thin film absorbs some light that could have been reflected to the person looking at the diamond. Water, dirt, or grease on the bottom of a diamond interferes with the diamond's brilliance and fire. Dirt or grease on the top of a diamond reduces its luster. A clean diamond is more brilliant and fiery than the same diamond when it is "dirty".

Although it is not one of the four Cs, cleanliness affects a diamond's beauty as much as any of the four Cs. Since the per carat price of diamond shifts around key milestones (such as 1.00 carat), many one-carat diamonds are the result of compromising "Cut" for "Carat." Some jewelry experts advise consumers to buy a 0.99 carat diamond for its better price or buy a 1.10 carat diamond for its better cut, avoiding a 1.00 carat diamond which is more likely to be a poorly cut stone. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the carat rating. Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%.

Oddly shaped crystals such as macles are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. The choice of cut is often decided by the original shape of the rough stone, location of the inclusions and flaws to be eliminated, the preservation of the weight, popularity of certain shapes amongst consumers and many other considerations. The process of shaping a rough diamond into a polished gemstone is both an art and a science.

EightStar Diamond has results of the FireScope. Hearts on Fire Diamond has results of the Hearts and Arrows viewer. Solasfera Diamond has results of Hearts and Arrows viewer, GemEx BrillianceScope, and FireScope. Along with this shift there are a few companies that provide results on these viewers and machines in addition to the original 4c's.

These viewers and machines often help consumers determine the light preformance results of the diamond in addition the the traditional 4 C's. SymmetriScope or IdealScope (tests for light leakage, light return and proportions), Hearts and Arrows Viewer (test for "hearts and arrows" characteristic pattern observable on stones exhibiting high symmetry), GemEx BrillianceScope (tests for direct light performance results of a diamond), Isee2 Machine (tests for diffused light performance results of a diamond), and ASET (test for AGS cut grade). They included the FireScope, a.k.a. A number of specially modified viewers and machines have been developed toward this end.

Recently, there has been a shift away from grading cut by the use of various angles and proportions toward measuring the performance of a cut stone. Several different theories on the "ideal" proportions of a diamond have been and continue to be advocated by professional gemologists. An inferior cut will produce a stone that appears dark at the center and in some extreme cases the ring settings may show through the top of the diamond as shadows. A well executed round brilliant cut should reflect most light out from the tabletop and make the diamond appear white when viewed from the top.

For a round brilliant cut, there is a balance between "brilliance" and "fire." When a diamond is cut for too much "fire," it looks like a cubic zirconia, which gives off much more "fire" than real diamond. A poorly cut diamond with facets cut only a few degrees out of alignment can result in a poorly performing stone. A number of factors, including proportion, symmetry, and the relative angles of various facets, are determined by the quality of the cut and can affect the performance of a diamond. In addition to carrying the most importance to a diamond's quality as a gemstone, the cut is also the most difficult to quantitatively judge.

The skill with which a diamond is cut determines its ability to reflect and refract light. The quality of a diamond's cut is widely considered the most important of the four Cs in determining the beauty of a diamond; indeed, it is commonly acknowledged that a well-cut diamond can appear to be of greater carat weight, and have clarity and color appear to be of better grade than they actually are. These newly developed cuts are viewed by many as more of an attempt at brand differentiation by diamond sellers, than actual improvements to the state of the art. Some of these include extra facets.

The past decades have seen the development of new diamond cuts, often based on a modification of an existing cut. The princess cut is also popular amongst diamond cutters: of all the cuts, it wastes the least of the original crystal. Cuts are influenced heavily by fashion: the baguette cut—which accentuates a diamond's luster and downplays its fire—was all the rage during the Art Deco period, whereas the princess cut—which accentuates a diamond's fire rather than its luster—is currently gaining popularity. Generally speaking, these "fancy cuts" are not held to the same strict standards as Tolkowsky-derived round brilliants and there are less specific mathematical guidelines of angles which determine a well-cut stone.

Diamonds which are not cut to the specifications of Tolkowsky's round brilliant shape (or subsequent variations) are known as "fancy cuts." Popular fancy cuts include the baguette (from the French, resembling a loaf of bread), marquise, princess (square outline), heart, briolette (a form of the rose cut), and pear cuts. Diamonds are cut into a variety of shapes that are generally designed to accentuate these features. Diamonds do not show all of their beauty as rough stones; instead, they must be cut and polished to exhibit the characteristic fire and brilliance that diamond gemstones are known for. Mathematically, the diameter in millimeters of a round brilliant should approximately equal 6.5 times the cube root of carat weight, or 11.1 times the cube root of gram weight.

Typically a round brilliant 1.0 carat diamond should have a diameter of about 6.5 mm. Another quick indication is the overall diameter. "Ideal" round brilliant diamonds should not have a depth percentage greater than 62.5%. The depth percentage is the overall quickest indication of the quality of the cut of a round brilliant.

So a poorly cut 1.0 carat diamond may have the same diameter and appear as large as a 0.85 carat diamond. Neither of the these tactics make the diamond appear any bigger, but it also greatly reduces the sparkle of the diamond. There is a financial premium for a diamond that weighs the magical 1.0 carat, so often the girdle is made thicker or the depth is increased. However, there is a small range in which the diamond can be considered "ideal." Today, because of the relative importance of carat weight in society, many diamonds are often intentionally cut poorly to increase carat weight.

The further the diamond's characteristics are from Tolkowsky's ideal, the less light will be reflected. A normal girdle should be about 1%–2% of the overall diameter. However, a thin girdle is required in reality in order to prevent the diamond from easily chipping in the setting. Tolkowsky's ideal dimensions did not include a girdle.

This should be a negligible diameter, otherwise light leaks out of the bottom. The culet is the tiny point at the bottom of the diamond. Tolkowsky defines the ideal dimensions to have:. The function of the crown is to diffuse light into various colors and the pavilion's function to reflect light back through the top of the diamond.

The girdle is the thin unpolished middle. The modern round brilliant has 57 facets (polished faces), counting 33 on the crown (the top half), and 24 on the pavilion (the lower half). He developed the round brilliant cut by calculating the ideal shape to return and scatter light when a diamond is viewed from above. The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky.

Round brilliant diamonds, the most common, are guided by these specific guidelines, though fancy cut stones are not able to be as accurately guided by mathematical specifics. There are mathematical guidelines for the angles and length ratios at which the diamond is supposed to cut at in order to reflect the maximum amount of light. Often diamond cut is confused with "shape.". The cut of a diamond describes the quality of workmanship and the angles to which a diamond is cut.

The cut of a diamond describes the manner in which a diamond has been shaped and polished from its beginning form as a rough stone to its final gem proportions. Diamond cutting is the art and science of creating a gem-quality diamond out of mined rough. Gemologists have developed rating systems for fancy colored diamonds, but they are not in common use because of the relative rarity of colored diamonds. Intense yellow coloration is considered one of the fancy colors, and is separate from the color grades of white diamonds.

Diamonds with unusual or intense coloration are sometimes labeled "fancy" by the diamond industry. A variety of impurities and structural imperfections cause different colors in diamonds, including yellow, pink, blue, red, green, brown, and other hues. While even a pale pink or blue hue may increase the value of a diamond, more intense coloration is usually considered more desirable and commands the highest prices. In contrast to yellow or brown hues, diamonds of other colors are much rarer and more valuable.

N-Y are usually appear light yellow or brown. Diamonds graded D-F are considered "colorless", G-J are considered "near-colorless", K-M are "slightly colored". Oddly enough, diamonds graded Z are also rare, and the bright yellow color is also highly valued. Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades.

The system uses a benchmark set of either natural diamonds of known color grade, or precision-crafted cubic zirconia; test lighting conditions are also standardized and carefully controlled. The GIA has developed a rating system for color in white diamonds, from "D" to "Z" (with D being "colorless" and Z having a bright yellow coloration), which has been widely adopted in the industry and is universally recognized, superseding several older systems once used in different countries. This effect is present in almost all white diamonds; in only the rarest diamonds is the coloration due to this effect undetectable. The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint.

Most diamonds used as gemstones are basically transparent with little tint, or white diamonds. For example, most white diamonds are discounted in price as more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice.

However, in reality almost no gem-sized natural diamonds are absolutely perfect. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. (see the main article for more detail). Diamonds are graded by the major societies on a scale ranging from Flawless to Imperfect.

Large cracks close to or breaking the surface may reduce a diamond's resistance to fracture. However, large clouds can affect a diamond's ability to transmit and scatter light. Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity. Those that do not have a visible inclusion are known as "eye-clean" and are preferred by most buyers, although visible inclusions can sometimes be hidden under the setting in a piece of jewelry.

Of that top 20 percent, a significant portion contains an inclusion or inclusions that are visible to the naked eye upon close inspection. Only about 20 percent of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone; the other 80 percent are relegated to industrial use. Diamonds become increasingly rare when considering higher clarity gradings. The Gemological Institute of America (GIA) and others have developed systems to grade clarity, which are generally based on those inclusions which are visible to a trained professional when a diamond is viewed from above, under 10x magnification.

The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. Clarity is a measure of internal defects of a diamond called inclusions. is also widely used for diamond necklaces, bracelets and other similar jewelry pieces.

T.c.w. when placed for sale, indicating the mass of the diamonds in both earrings and not each individual diamond. Diamond solitaire earrings, for example, are usually quoted in t.c.w. Total carat weight (t.c.w.) is a phrase used to describe the total mass of diamonds or other gemstone in a piece of jewelry, when more than one gemstone is used.

Because of this, diamond prices (particularly among wholesalers and other industry professionals) are often quoted per carat, rather than per stone. For example, a buyer may place an order for 100 carats of 0.5 carat, D–F, VS2-SI1, excellent cut diamonds, indicating he wishes to purchase 200 diamonds (100 carats total mass) of those approximate characteristics. In the wholesale trade of gem diamonds, carat is often used in denominating lots of diamonds for sale. Jewelers often trade diamonds at negotiated discounts off the Rapaport price (e.g., "R -3%").

A weekly price list published by Rapaport of New York, of diamond prices per carat, for different diamond cuts, clarity and weights, is currently considered the de-facto retail price baseline. As an example, a 0.95 carat diamond may have a significantly lower price per carat than a comparable 1.05 carat diamond, because of differences in demand. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than a milestone than for those weighing just less. The price per carat does not increase smoothly with increasing size.

A review of comparable diamonds available for purchase in September 2005 demonstrates this effect (approximate prices for round cut, G color, VS2 diamonds with "1A" cut grade, as listed on http://www.pricescope.com):. All else being equal, the value of a diamond increases exponentially in relation to carat weight, since larger diamonds are both rarer and more desirable for use as gemstones. The point unit—equal to one one-hundredth of a carat (0.01 carat, or 2 mg)—is commonly used for diamonds of less than one carat. One carat is defined as exactly 200 milligrams (about 0.007 ounce).

The carat weight measures the mass of a diamond. While carat weight and cut angles are mathematically defined, the clarity and color are judged by the trained human eye and are therefore open to slight variance in interpretation. There are four major gemological associations which "certify" diamonds: that is, define the four Cs of a diamond. Cleanliness also dramatically affects a diamond's beauty.

These characteristics include physical characteristics such as the presence of fluorescence, as well as data on a diamond's history including its source and which gemological institute performed evaluation services on the diamond. Other characteristics not described by the four Cs can and do influence the value or appearance of a gem diamond. Consumers who purchase individual diamonds are often advised to use the four Cs to pick the diamond that is "right" for them; to these is sometimes added the "fifth C" of cost. More detailed information from within each characteristic can then be used to determine actual market value for individual stones.

Most gem diamonds are traded on the wholesale market based on single values for each of the four Cs; for example knowing that a diamond is rated as 1.5 carats, VS2 clarity, F color, excellent cut, is enough to reasonably establish an expected price range. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, clarity, color, and cut. Over time, especially since around 1900, experts in the field of gemology have developed methods of characterizing diamonds and other gemstones based on the characteristics most important to their value as a gem. The dispersion of white light into a rainbow of colors, known in the trade as fire, is the other primary characteristic of gem diamonds, and has been highly prized throughout history.

The use of diamonds as gemstones of decorative value is the most familiar use to most people today, and is also the earliest use, with decorative use of diamonds stretching back into antiquity. Diamonds can also be brought to the surface through certain processes which may occur when two continental plates collide forcefully, although this phenomenon is less understood and currently assumed to be uncommon. Diamonds have also rarely been found in deposits left behind by glaciers (notably in Wisconsin and Indiana); however, in contrast to alluvial deposits, glacial deposits are not known to be of significant concentration and are therefore not viable commercial sources of diamond. These include alluvial deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate because of their approximate size and density.

Secondary sources of diamonds include all areas where a significant number of diamonds, eroded out of their kimberlite or lamproite matrix, accumulate because of water or weather action. A volcanic pipe containing diamonds is known as a primary source of diamonds. Once diamonds have been forced to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area. Kimberlite deposits are known as blue ground for the deeper serpentinized part of the deposits, or as yellow ground for the near surface smectite clay and carbonate weathered and oxidized portion.

The most common indicator minerals are chromian garnets (usually bright red Cr-pyrope, and occasionally green ugrandite-series garnets), eclogitic garnets, orange Ti-pyrope, red high chromian spinels, dark chromite, bright green Cr-diopside, glassy green olivine, black picroilmenite, and magnetite. These minerals are rich in chromium (Cr) or titanium (Ti), elements which impart bright colors to the minerals. Certain indicator minerals typically occur within diamondiferous kimberlites and are used as mineralogic tracers in the search for diamond deposits by prospectors. These rocks are characteristically rich in magnesium bearing olivine, pyroxene, and amphibole minerals which are usually altered to serpentine under near surface conditions.

The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks and material upward. The magma in such volcanic pipes is usually one of two characteristic types, which cool into igneous rock known as either kimberlite or lamproite. Diamond-bearing volcanic pipes are most commonly found in the oldest regions of continental crust, which relates to the fact that these areas are the coolest portions of the earth's crust, and therefore diamonds can form at the shallowest depths. Below these typically small surface volcanic craters are formations known as volcanic pipes, which contain material that was pushed toward the surface of the earth by volcanic action, but did not erupt before the volcanic activity ceased.

The magma for such a volcano must originate at a depth where diamonds can be formed, 90 miles (150 km) deep or more (three times or more the depth of source magma for most volcanoes); this is a relatively rare occurrence. Diamond-bearing rock is forced close to the surface through deep-origin volcanic eruptions. Microdiamonds are now used as one indicator of ancient meteorite impact sites. Very small diamonds, known as microdiamonds or nanodiamonds, have been found in impact craters where meteors strike the Earth and create shock zones of high pressure and temperature where diamond formation can occur.

Diamonds can also form in other natural high-pressure, high-temperature events. Diamonds (especially those from secondary deposits) are commonly found coated in nyf, an opaque gum-like skin. This is all due to the conditions in which they form. Sometimes they are found grown together or form double "twinned" crystals grown together at the surfaces of the octahedron.

The crystals can have rounded off and unexpressive edges and can be elongated. As diamond's crystal structure has a cubic arrangement of the atoms, they have many facets that belong to a cube, octahedron, rhombicosidodecahedron, tetrakis hexahedron or disdyakis dodecahedron. Diamonds occur most often as euhedral or rounded octahedra and twinned octahedra known as macles. Diamonds that have come to the Earth's surface are generally very old, ranging from under 1 billion to 3.3 billion years old.

These two different source carbons have measurably different ¹³C:¹²C ratios. In contrast, eclogitic diamonds contain organic carbon from organic detritus that has been pushed down from the surface of the Earth's crust through subduction (see plate tectonics) before transforming into diamond. Some diamonds, known as harzburgitic, are formed from inorganic carbon originally found deep in the Earth's mantle. Through studies of carbon isotope ratios (similar to the methodology used in carbon dating) except using the stable isotopes C-12 and C-13, it has been shown that the carbon found in diamonds comes from both inorganic and organic sources.

Long periods of exposure to these high pressures and temperatures allow diamond crystals to grow larger. Diamond formation under oceanic crust takes place at greater depths because of higher temperatures, which require higher pressure for diamond formation. Under continental crust, diamonds form starting at depths of about 150 kilometers (90 miles), where pressure is roughly 5 gigapascals and the temperature is around 1200 degrees Celsius (2200 degrees Fahrenheit). On Earth, the formation of diamonds is possible because there are regions deep within the Earth that are at a high enough pressure and temperature that the formation of diamonds is thermodynamically favorable (see the diamond phase diagram and geotherms here).

Diamond is formed by prolonged exposure of carbon bearing materials to high pressure and temperature.
. Because diamond has such high thermal conductance it is already used in semiconductor manufacture to prevent silicon and other semiconducting materials from overheating. Specially purified synthetic diamond has the highest thermal conductivity (2000–2500 W/(m·K), five times more than copper) of any known solid at room temperature.

Most natural blue diamonds contain boron atoms which replace carbon atoms in the crystal matrix, and also have high thermal conductivity. Unlike most electrical insulators, diamond is a good conductor of heat because of the strong covalent bonding within the crystal. Blue diamonds which are not boron-doped, such as those recently recovered from the Argyle diamond mine in Australia that owe their color to an overabundance of hydrogen atoms, are not semiconductors. Blue diamonds owe their semiconductive property to boron impurities, which act as a doping agent and cause p-type semiconductor behavior.

Except for most blue diamonds, which are semiconductors, diamonds are good electrical insulators. Most diamonds show no fluorescence although colored diamonds show a wider range of fluorescence than the blue fluorescence normally observed in clear diamonds. Nearly all diamonds fluoresce bluish-white, yellow or green under X-rays and this property is used extensively in mining to separate the fluorescing diamond from the non-fluorescing rock. Some diamonds exhibit fluorescence of various colors (predominately blue) under long wave ultraviolet light.

This is owed to their high refractive index of 2.417 (at 589.3 nm), which causes total internal reflection to occur. The luster of a diamond, a characterization of how light interacts with the surface of a crystal, is brilliant and is described as adamantine, which simply means diamond-like. This strong ability to split white light into its component colors is an important aspect of diamond's attraction as a gemstone, giving it impressive prismatic action that results in so-called fire in a well-cut stone. Diamonds exhibit a high dispersion of visible light.

However, owing to a very large kinetic energy barrier, diamonds are metastable; under normal conditions, it would take an extremely long time (possibly more than the age of the Universe) for diamond to decay into graphite. This was shown in the late 18th century, and previously described during Roman times. Diamonds will burn at approximately 800 degrees Celsius, providing that enough oxygen is available. At surface air pressure (one atmosphere), diamonds are not as stable as graphite, and so the decay of diamond is thermodynamically favorable (ΔG = −2.99 kJ / mol).

The most common impurity, nitrogen, causes a yellowish or brownish tinge. Most diamond impurities replace a carbon atom in the crystal lattice. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Diamonds with a detectable hue to them are known as colored diamonds.

Diamonds occur in a variety of transparent hues — colorless, white, steel, blue, yellow, orange, red, green, pink, brown—or colored black. Diamonds cut into certain particular shapes are therefore more prone to breakage than others. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Toughness relates to a material's ability to resist breakage from forceful impact.

Unlike hardness, which only denotes resistance to scratching, diamond's toughness is only fair to good. Unlike many other gems, it is well-suited to daily wear because of its resistance to scratching—perhaps contributing to its popularity as the preferred gem in an engagement ring or wedding ring, which are often worn every day. Because it can only be scratched by other diamonds, it maintains its polish extremely well, keeping its luster over long periods of time. The hardness of diamonds also contributes to its suitability as a gemstone.

Industrial applications, especially as drill bits and engraving tools, also date to ancient times. Industrial-grade diamonds are either unsuitable for use as gems or synthetically produced, which lowers their price and makes their use economically feasible. Other specialized applications also exist or are being developed, including use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most other diamonds, which are excellent electrical insulators. Common industrial adaptations of this ability include diamond-tipped drill bits and saws, or use of diamond powder as an abrasive.

As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. It is one of the most known and most useful of more than 3,000 known minerals. Industrial use of diamonds has historically been associated with their hardness; this property makes diamond the ideal material for cutting and grinding tools. 1990).

Most other diamonds show more evidence of multiple growth stages, which produce inclusions, flaws and defect planes in the crystal lattice all of which affect their hardness (Taylor et al. Their hardness is considered to be a product of the crystal growth form, which is single stage growth crystal. These diamonds are generally small, perfect to semiperfect octahedra and are used to polish other diamonds. The hardest diamonds in the world are diamonds from the New England area in New South Wales, Australia.

However, aggregated diamond nanorods, an allotrope of carbon first synthesized in 2005, are now believed to be even harder than diamond. Diamond's hardness has been known since antiquity, and is the source of its name. Diamond is the hardest known naturally occurring material, scoring 10 on the relative Mohs scale of mineral hardness and having an absolute hardness value of between 167 and 231 gigapascals in various tests. A colorless, grey or black diamond with a tiny radial structure is a spherulite.

A cryptocrystalline variety of diamond is called carbonado. Lonsdaleite is a polymorph of diamond (and a distinct mineral species) that crystallizes with hexagonal symmetry; it is rarely found in nature, but is characteristic of synthetic diamonds. Other elements of the carbon group such as silicon have forms analogous to diamond. Graphite, another allotrope of carbon, has a rhombohedral crystal structure and as a result shows dramatically different physical characteristics — contrary to diamond, graphite is a very soft, dark grey, opaque mineral.

The tetrahedral arrangement of atoms in a diamond crystal is the source of many of diamond's properties. The unit cell of diamond has a two atom basis at (0,0,0) and (1/4,1/4,1/4), which means half of the atoms are at lattice points and the other half are offset by (1/4,1/4,1/4), where 1 is the length of a side of the unit cell. Diamonds typically crystallize in the face-centered cubic crystal system and consist of tetrahedrally bonded carbon atoms. These properties form the basis for most modern applications of diamond.

Most notable among these properties are the extreme hardness of diamond, its high dispersion index, and high thermal conductivity. Humans have been able to adapt diamonds for many uses because of the material's exceptional physical characteristics. Diamond is a transparent crystal of pure carbon consisting of tetrahedrally bonded carbon atoms. See also: Crystallographic defects in diamond.

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. There are also allegations that the De Beers Group misuses its dominance in the industry to control supply and manipulate price via monopolistic practices. The mining and distribution of natural diamonds are subjects of frequent controversy—such as with concerns over the sale of conflict diamonds by African paramilitary groups.

They are generally mined from volcanic pipes, which are deep in the Earth where the high pressure and temperature enables the formation of the crystals. Most natural diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, Russia, Brazil, and Australia. Although nearly four times the mass of natural diamonds are produced as synthetic diamond each year, the vast majority of synthetic diamond production remains small, imperfect diamonds suitable only for industrial-grade use, with gem-quality synthetic diamonds only recently becoming available. Popularity of diamonds has risen since the 19th century because of improved cutting and polishing techniques, and they are commonly judged by the "four Cs": carat, clarity, color, and cut.

They have been treasured as gems since their use as religious icons in India at least 2,500 years ago—and usage in drill bits and engraving tools also dates to early human history. The name "diamond" derives from the ancient Greek adamas (αδάμας; "impossible to tame"). About 130 million carats (26,000 kg) are mined annually, with a total value of nearly USD $9 billion. Diamonds are specifically renowned as a mineral with superlative physical qualities - they make excellent abrasives because they can only be scratched by other diamonds, which also means they hold a polish extremely well and retain luster.

Diamond is one of the two best known forms (or allotropes) of carbon, whose hardness and high dispersion of light make it useful for industrial applications and jewelry (the other equally well known allotrope is graphite). Crown Depth (Depth of crown divided by crown diameter) = 16.2%. Pavilion Depth (Depth of pavilion divided by overall diameter) = 43.1%. Crown Angle (Angle between the girdle and the crown) = 34.5°.

Pavilion Angle (Angle between the girdle and the pavilion) = 40.75°. Depth percentage (Overall depth divided by the overall diameter) = 59.3%. Table percentage (table diameter divided by overall diameter) = 53%. European Gemological Laboratory (EGI) has a similar reputation to the IGL.

International Gemological Laboratory (IGL) is a generally respected laboratory but suffers from a negative industry reputation for its grading practices, which are perceived by critics as being either less conservative or less consistent than the GIA and AGS. American Gemological Society (AGS) is not as widely recognized nor as old as the GIA, but garners an equally high reputation. Gemological Institute of America (GIA) was the first laboratory to issue modern diamond reports, and holds the highest reputation amongst gemologists for its consistent, conservative grading.