This article is about the mineral. For the gemstone, see Diamond (gemstone).
For other uses, including the shape ◊, see Diamond (disambiguation).
A scattering of round-brilliant cut diamonds shows off the many reflecting facets.
Category Native Minerals
Chemical formula C
Molar mass 12.01 g·mol-1
Color Typically yellow, brown or gray to colorless. Less often blue, green, black, translucent white, pink, violet, orange, purple and red.
Crystal habit Octahedral
Crystal system Isometric-Hexoctahedral (Cubic)
Cleavage 111 (perfect in four directions)
Fracture Conchoidal (shell-like)
Mohs scale hardness 10
Diaphaneity Transparent to subtransparent to translucent
Specific gravity 3.52±0.01
Density 3.5–3.53 g/cm3
Polish luster Adamantine
Optical properties Isotropic
Refractive index 2.418 (at 500 nm)
Melting point Pressure dependent
In mineralogy, diamond (from the ancient Greek αδάμας – adámas “unbreakable”) is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools.
... forms. There are octahedral, cubic, and dodecahedral diamond crystals. The octahedral crystals are formed with eight sides, the cubic ones ... are spaced at relatively wide distances from one another. Diamond crystals may sometimes be very symmetrical, but they are not ... an octahedral face. Therefore, when powdered diamond is used to cut a diamond crystal, the powder will always contain some particles ...
Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, that is ability to disperse light of different colors, which results in its characteristic luster. Excellent optical and mechanical properties, combined with efficient marketing, make diamond the most popular gemstone.
Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth).
Diamonds are brought close to the Earth surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites. Diamonds can also be produced synthetically in a high-pressure high-temperature process which approximately simulates the conditions in the Earth mantle. An alternative, and completely different growth technique is chemical vapor deposition (CVD).
Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have been specially developed to distinguish natural and synthetic diamonds and diamond simulants.Contents [hide]
2 Material properties
2.2 Electrical conductivity
... all about, we must dig deeper and know the characteristics of Earth that we haven’t yet know. `The completion of this ... surface environment of the Moon, and by inference, to the Earth. Earth’s atmosphere and oceans formed by volcanic activity and ... mya and then intensified during the Pleistocene about 3 mya. High-latitude regions have since undergone repeated cycles of glaciation and ...
3 Natural history
3.1 Formation in cratons
3.2 Formation in meteorite impact craters
3.3 Extraterrestrial formation
4.1 Controversial sources
5 Commercial markets
5.1 Gemstones and their distribution
5.2 Industrial uses
6 Synthetics, simulants, and enhancements
7 See also
10 External links
See also: Diamond (gemstone)
The name diamond is derived from the ancient Greek αδάμας (adámas), “proper”, “unalterable”, “unbreakable, untamed”, from ἀ- (a-), “un-” + δαμάω (damáō), “I overpower, I tame”. Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could be found many centuries ago along the rivers Penner, Krishna and Godavari. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years.
Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history. The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.
In 1772, Antoine Lavoisier used a lens to concentrate the rays of the sun on a diamond in an atmosphere of oxygen, and showed that the only product of the combustion was carbon dioxide, proving that diamond is composed of carbon. Later in 1797, Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite (charcoal) releases the same amount of gas he established the chemical equivalence of these substances.
The most familiar use of diamonds today is as gemstones used for adornment, a use which dates back into antiquity. The dispersion of white light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon.
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Main articles: Material properties of diamond and Crystallographic defects in diamond
Theoretically predicted phase diagram of carbon
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in structure.
A diamond is a transparent crystal of tetrahedrally bonded carbon atoms (sp3) that crystallizes into the diamond lattice which is a variation of the face centered cubic structure. Diamonds have been adapted for many uses because of the material’s exceptional physical characteristics. Most notable are its extreme hardness and thermal conductivity (900–2,320 W·m−1·K−1), as well as wide bandgap and high optical dispersion. Above 1,700 °C (1,973 K / 3,583 °F) in vacuum or oxygen-free atmosphere, diamond converts to graphite; in air, transformation starts at ~700 °C. Naturally occurring diamonds have a density ranging from 3.15–3.53 g/cm3, with pure diamond close to 3.52 g/cm3. Despite the hardness of diamonds, the chemical bonds that hold the carbon atoms in diamonds together are weaker than those that hold together the other form of pure carbon, graphite. The difference is that in diamonds, the bonds form an inflexible three-dimensional lattice. In graphite, the atoms are tightly bonded into sheets, which can slide easily over one another.
Diamond is the hardest natural material known, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest) using the Mohs scale of mineral hardness. Diamond has a hardness of 10 (hardest) on this scale. Diamond’s hardness has been known since antiquity, and is the source of its name.
Diamond hardness depends on its purity, crystalline perfection and orientation: hardness is higher for flawless, pure crystals oriented to the direction (along the longest diagonal of the cubic diamond lattice). Therefore, whereas it might be possible to scratch some diamonds with other materials, such as boron nitride, the hardest diamonds can only be scratched by other diamonds. In particular, nanocrystalline diamond aggregates were measured to be harder than any large single crystal diamond. Those aggregates are produced by high-pressure high-temperature treatment of graphite or fullerite (C60).
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The hardness of diamond contributes to its suitability as a gemstone. Because it can only be scratched by other diamonds, it maintains its polish extremely well. 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 engagement or wedding rings, which are often worn every day.
The hardest natural diamonds mostly originate from the Copeton and Bingara fields located in the New England area in New South Wales, Australia. These diamonds are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds. Their hardness is associated with the crystal growth form, which is single-stage crystal growth. 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. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds that are harder than the diamonds used in hardness gauges.
Somewhat related to hardness is another mechanical property toughness, which is a material’s ability to resist breakage from forceful impact. The toughness of natural diamond has been measured as 2.0 MPa·m1/2, and the critical stress intensity factor is 3.4 MN·m−3/2. Those values are good compared to other gemstones, but poor compared to most engineering materials. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamond has a cleavage plane and is therefore more fragile in some orientations than others. Diamond cutters use this attribute to cleave some stones, prior to faceting.
Other specialized applications also exist or are being developed, including use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most diamonds, which are excellent electrical insulators. The conductivity and blue color originate from boron impurity. Boron substitutes for carbon atoms in the diamond lattice, donating a hole into the valence band.
... The atoms in a crystal are in a regular repeating pattern called the crystal lattice... A crystal lattice is defined by a ... crystals o Molecular crystals o Infinite arrays: SS Metallic crystals SS Ionic crystals SS Continuous covalent crystals web > Metals possess a crystal lattice ... in a periodic pattern called a crystal lattice. In each type of crystal structure a certain fundamental grouping of ...
Substantial conductivity is commonly observed in nominally undoped diamond grown by chemical vapor deposition. This conductivity is associated with hydrogen-related species adsorbed at the surface, and it can be removed by annealing or other surface treatments.
Main article: Diamond color
Brown diamonds at the National Museum of Natural History in Washington, D.C
Diamond has a wide bandgap of 5.5 eV corresponding to the deep ultraviolet wavelength of 225 nanometers. This means pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents).
Transition metals Ni and Co, which are commonly used for growth of synthetic diamond by high-pressure high-temperature techniques, have been detected in diamond as individual atoms; the maximum concentration is 0.01% for Ni and even much less for Co. Virtually any element can be introduced to diamond by ion implantation.
Nitrogen is by far the most common impurity found in gem diamonds. Nitrogen is responsible for the yellow and brown color in diamonds. Boron is responsible for the gray blue colors. Color in diamond has two additional sources: irradiation (usually by alpha particles), that causes the color in green diamonds; and plastic deformation of the diamond crystal lattice. Plastic deformation is the cause of color in some brown and perhaps pink and red diamonds. In order of rarity, colorless diamond, by far the most common, is followed by yellow and brown, by far the most common colors, then by blue, green, black, translucent white, pink, violet, orange, purple, and the rarest, red. “Black”, or Carbonado, diamonds are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the crystal lattice, known as a carbon flaw. The most common impurity, nitrogen, causes a slight to intense yellow coloration depending upon the type and concentration of nitrogen present. The Gemological Institute of America (GIA) classifies low saturation yellow and brown diamonds as diamonds in the normal color range, and applies a grading scale from “D” (colorless) to “Z” (light yellow).
... , and green. 3. List the 6 tertiary colors. The 6 tertiary colors are blue-violet, blue-green, red-orange, red-violet, yellow-green ... -orange, red-orange, and rose. 19. List 6 cool colors. Six cool colors are blue, green, violet, blue-green, blue-violet, and sky ... the 3 Primary Colors. The primary colors are blue, red, and yellow. 2. List the 3 Secondary Colors. The secondary colors are purple, orange ...
Diamonds of a different color, such as blue, are called fancy colored diamonds, and fall under a different grading scale.
In 2008, the Wittelsbach Diamond, a 35.56-carat (7.11 g) blue diamond once belonging to the King of Spain, fetched over US$24 million at a Christie’s auction. In May 2009, a 7.03-carat (1.41 g) blue diamond fetched the highest price per carat ever paid for a diamond when it was sold at auction for 10.5 million Swiss francs (6.97 million Euro or US$9.5 million at the time). That record was however beaten the same year: a 5-carat vivid pink diamond was sold for $10.8 million in Hong Kong on December 1, 2009.