| Diamond | |
|---|---|
 A scattering of round-brilliant cut diamonds shows off the many reflecting facets. | |
| General | |
| Category | Native Minerals |
| Chemical formula | C |
| Identification | |
| Molecular Weight | 12.01 u |
| Color | Typically yellow, brown or gray to colorless. Less often in blue, green, black, translucent white, pink, violet, orange, purple and red.[1] |
| Crystal habit | Octahedral |
| Crystal system | Isometric-Hexoctahedral (Cubic) |
| Cleavage | 111 (perfect in four directions) |
| Fracture | Conchoidal - step like |
| Mohs Scale hardness | 10[1] |
| Luster | Adamantine[1] |
| Polish luster | Adamantine[1] |
| Refractive index | 2.4175–2.4178 |
| Optical Properties | Singly Refractive[1] |
| Birefringence | none[1] |
| Dispersion | .044[1] |
| Pleochroism | none[1] |
| Ultraviolet fluorescence | colorless to yellowish stones - inert to strong in long wave, and typically blue. Weaker in short wave.[1] |
| Absorption spectra | In pale yellow stones a 415.5 nm line is typical. Irradiated and annealed diamonds often show a line around 594 nm when cooled to low temperatures.[1] |
| Streak | White |
| Specific gravity | 3.52 (+/- .01)[1] |
| Density | 3.5-3.53 g/cm³ |
| Diaphaneity | Transparent to subtransparent to translucent |
In mineralogy, diamond (from the ancient Greek ἀδάμας, adámas) is the allotrope of carbon where the carbon atoms are arranged in an isometric-hexoctahedral crystal lattice. Its hardness and high dispersion of light make it useful for industrial applications and jewelry. It is the hardest known naturally-occurring mineral. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds (known as Type-II diamonds) that are harder than the diamonds used in hardness gauges.[2] Presently, only aggregated diamond nanorods, a material created using ultrahard fullerite (C60) is confirmed to be harder, although other substances such as cubic boron nitride, rhenium diboride and ultrahard fullerite itself are comparable.
Diamonds are specifically renowned as a material with superlative physical qualities; they make excellent abrasives because they can be scratched only by other diamonds, borazon, ultrahard fullerite, rhenium diboride, or aggregated diamond nanorods, which also means they hold a polish extremely well and retain their lustre. Approximately 130 million carats (26,000 kg (57,000 lb)) are mined annually, with a total value of nearly USD $9 billion, and about 100,000 kg (220,000 lb) are synthesized annually.[3]
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