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
Cleavage	111
Fracture	Conchoidal
Mohs Scale hardness	10 1
Luster	Adamantine 1
Polish luster	Adamantine 1
Refractive index	2.41752.4178
Optical Properties	Singly Refractive 1
Birefringence	None 1
Dispersion	0.044 1
Pleochroism	None 1
Streak	White
Specific gravity	3.52 1
Density	3.5-3.53 g/cm

In mineralogy diamond is the allotrope of carbon where the carbon atoms are arranged in an isometric-hexoctahedral crystal lattice. After graphite diamond is the second most stable form of carbon. Its hardness and high dispersion of light make it useful for industrial applications and jewelry. It is the hardest known mineral. 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. ²

Diamonds are specifically renowned as a material with superlative physical qualities; they make excellent abrasives because few substances can scratch them. As a result they hold a polish extremely well and retain their lustre. Approximately 130&million carats are mined annually with a total value of nearly USD 9& billion and about 100000&kg are synthesized annually. ³