Diamond

The name diamond refers to its hardness (Greek - Adamas, unconquerable). There is nothing comparable to its hardnesses; it is therefore nearly imperishable. Compared to corundum, diamond's cutting resistance is 140 times greater. Although hardness is different in the individual crystal faces. This allows diamond to be cut by diamond (or diamond powder, in which - according to statistical probability - various diamond harness occur). Mounting care must be taken because of perfect cleavage. To the experienced eye, a diamond's strong luster can reveal the difference between a real diamond and it's imitations.

• Color : Colorless, yellow, brown, sometimes green, blue, reddish black
• Color of streak : None possible
• Mohs' hardness : 10
• Specific gravity : 3.47-3.55
• Cleavage : Perfect
• Fracture : Conchoidal to splintery
• Crystal system : Isometric (cubic) mainly octahedrons, also rhombic dodecahedrons, cubes, twins, plates
• Chemical composition : C, crystallized carbon
• Transparency: Transparent
• Refractive index: 2.417-2.419
• Double refraction: None, often anomalous
• Dispersion: 0.044
• Pleochroism: None
• Absorption spectrum Colorless to yellow: 4780, 4650,4510.4350, 4015.4230, 4155, 3900
  Blue-green: (5370), 5040 (4980)
• Fluorescence: Variable; Colorless and yellow: mostly blue
  Brown and green: often green