mineral

Ruby

Corundum (Al2O3) with Chromium traces

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

Hardness: 9 on Mohs scale
Color: Pinkish-red to deep blood-red
Luster: Vitreous to adamantine

Identified March 15, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in metamorphic rocks (schist or marble) or igneous rocks (alkali basalt) under high pressure and temperature. Major deposits are found in alluvial or eluvial placers where the minerals have weathered out of the host rock.

Uses & applications

Primary use is in high-end jewelry as a precious gemstone. Industrial applications include watch bearings, lasers, and high-durability optical windows (though synthetic ruby is more common for industry).

Geological facts

Ruby is one of the four 'precious' gemstones. The most valuable color is known as 'Pigeon's Blood' red. Rubies and Sapphires are technically the same mineral (Corundum), distinguished only by color.

Field identification & locations

Identify by its extreme hardness (can scratch almost any other mineral except diamond) and hexagonal crystal habit. Found in regions like Myanmar, Sri Lanka, Thailand, and Madagascar. Collectors look for clarity, saturation of color, and 'silk' inclusions.