Color : Colorless, yellow, brown, sometimes green, blue, reddish, black
Mohs’ hardness : 10 
Specific gravity : 3.47-3.55 
Cleavage : Perfect 
Crystal system : cubic 
Chemical composition : carbon
Refractive index : 2.417-2.419 
Double refraction : none
Flourescence : Variable ; colorless and yellow : mostly blue ; brown and green : mostly green

The name diamond refers to its hardness (Greek – Adamas, unconquerable). There is nothing comparable to it in hardness; it is therefore nearly imperishable. Its cutting resistance is 140 times greater than that of corundum. However the hardness of a diamond is different in the individual crystal faces. This allows one to cut diamond with a diamond (or diamond powder, in which according to statistical probability – various diamond hardnesses occur). Care has to be taken during mounting because of perfect cleavage. Its very strong luster enables the experienced eye to differentiate between a diamond and its imitations.