gemstone

Diamond

Carbon (C)

Hardness: 10 on the Mohs scale (hardest known natural material); Color: colorless, yellow, brown, white, or rare fancy colors; Luster: adamantine; Crystal structure: isometric (cubic); Cleavage: perfect octahedral; Specific gravity: 3.51-3.53

Hardness: 10 on the Mohs scale (hardest known natural material)
Color: colorless, yellow, brown, white, or rare fancy colors
Luster: adamantine

Identified July 28, 2026More gemstone →

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Physical properties

Formation & geological history

Formed under high-pressure, high-temperature conditions in Earth's mantle, typically at depths of 150-250 kilometers, and brought to the surface through deep-seated volcanic eruptions of kimberlite or lamproite magmas, dating from billions of years ago.

Uses & applications

Widely used in high-end fine jewelry and engagement rings, as well as crucial industrial applications including cutting, grinding, drilling, and polishing tools due to its extreme hardness.

Geological facts

A large rough diamond like the one pictured is exceptionally rare and valuable. Diamonds are made of pure carbon and are thermally stable only under extreme mantle conditions; at the surface, they are thermodynamically metastable.

Field identification & locations

Identified by its adamantine luster, extreme hardness (scratches all other minerals), high thermal conductivity, and distinctive crystal habits (such as octahedrons or rounded dodecahedrons).