Crystal system: cubic
Chemical Formula/composition: carbon
(only gemstone that is composed of a single element)
Crystal habit: octahedra, cubes,
tetrakishedrons, twinning possible
Hardness: 10 (hardest mineral)
Specific gravity: 3.514 - 3.518
Luster: adamantine to greasy
Toughness: good
Cleavage: perfect, octahedral
Optics: refractive index: 2.417
ND, Birefringence: none (isotropic), Dispersion: 0.044 (extremely high)
Color: colorless, pale yellow less
commonly red, orange, yellow, pink, green, blue, brown, and black (carbonado)
Other: U.V. fluorescence commonly
nonfluorescent, fluoresces blue, green, yellow or red
Varieties: gem
quality, industrial quality (called bort or carbonado).
Localities: Southern
Africa, Brazil, Canada, China, Russia, British Guiana, India, in the USA
(Arizona, Nevada, and Montana, and most importantly Pike County, Arkansas),
and space dust/meteroites
Common simulants
CZ = cubic zirconia, GGG = gadolinium gallium garnet, SiC = Silicon Carbide
aka Moissonite, Strontium titanate, YAG = yttrium aluminum garnet, other
simulants include "paste", a type of high refractive index glass
Synthetics: Synthetic gem quality
diamonds are now being marketed by several firms in the USA; other major
sources include: Russia and De Beers
Detailed Subject descriptions