gemstone

Diamond

Carbon (C)

Hardness: 10 (Mohs scale), Color: Clear/Colorless, Luster: Adamantine, Crystal Structure: Cubic/Isometric, Cleavage: Perfect in four directions. High refractive index (2.417) and dispersion.

Identified July 10, 2026More gemstone →

Explore Diamond in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 10 (Mohs scale), Color: Clear/Colorless, Luster: Adamantine, Crystal Structure: Cubic/Isometric, Cleavage: Perfect in four directions. High refractive index (2.417) and dispersion.

Formation & geological history

Formed under extreme pressure and temperature conditions deep (approx 150-200km) within the Earth's mantle over billions of years, then transported to the surface via kimberlite or lamproite volcanic eruptions.

Uses & applications

Extensively used in fine jewelry (engagement rings, necklaces), and industrially as an abrasive for cutting, drilling, and grinding due to its unmatched hardness.

Geological facts

Diamond is the hardest natural substance known to man. It is a polymorphic form of carbon, sharing the same chemical element as graphite but with a much stronger tetrahedral crystal lattice.

Field identification & locations

Identify by testing thermal conductivity, checking for a high refractive index (sparkle), and hardness tests. Found naturally in kimberlite pipes or alluvial deposits (river beds).