gemstone

Ruby / Pink Sapphire

Corundum (Al2O3 with Chromium impurities)

Hardness: 9 on Mohs scale; Color: Pinkish-red to purplish-pink; Luster: Vitreous to sub-adamantine; Crystal system: Trigonal/Hexagonal; Cleavage: None (has parting); Specific gravity: 3.97-4.05

Hardness: 9 on Mohs scale
Color: Pinkish-red to purplish-pink
Luster: Vitreous to sub-adamantine

Identified July 20, 2026More gemstone →

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Physical properties

Hardness: 9 on Mohs scale; Color: Pinkish-red to purplish-pink; Luster: Vitreous to sub-adamantine; Crystal system: Trigonal/Hexagonal; Cleavage: None (has parting); Specific gravity: 3.97-4.05

Formation & geological history

Formed in metamorphic rocks such as marble or schist, or in igneous rocks like basalt. Small crystals like this are often found in alluvial placer deposits where they have weathered out of the host rock.

Uses & applications

Primarily used in jewelry as a gemstone. Industrial grade corundum is used for abrasives and in precision instruments due to its extreme hardness.

Geological facts

Ruby and sapphire are the same mineral (corundum); the color distinction is based on the concentration of chromium. In many trade circles, a lighter pink specimen is called a pink sapphire, while a deeper red is a ruby.

Field identification & locations

Identify by its extreme hardness (will scratch almost everything except diamond) and hexagonal crystal habit. Common locations include Myanmar, Sri Lanka, Madagascar, and Thailand.

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