mineral

Ruby (in jewelry)

Corundum (Al2O3 with Chromium traces)

Hardness: 9.0 on Mohs scale; Color: Deep red (Pigeon blood); Luster: Vitreous to subadamantine; Crystal Structure: Trigonal/Hexagonal; Specific Gravity: 3.97–4.05

Hardness: 9
Color: Deep red (Pigeon blood)
Luster: Vitreous to subadamantine

Identified May 24, 2026More mineral →

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Physical properties

Hardness: 9.0 on Mohs scale; Color: Deep red (Pigeon blood); Luster: Vitreous to subadamantine; Crystal Structure: Trigonal/Hexagonal; Specific Gravity: 3.97–4.05

Formation & geological history

Formed through regional or contact metamorphism of aluminous rocks or as a primary mineral in igneous rocks. Often found in marble-hosted deposits or basalt-hosted environments.

Uses & applications

Primary use in high-end jewelry (rings, necklaces, earrings), historical use as a gemstone of royalty, and industrial uses for lasers and watch bearings (synthetic varieties).

Geological facts

Ruby is the birthstone for July. The presence of chromium gives it both its red color and its characteristic fluorescence. It is the second hardest natural mineral after diamond.

Field identification & locations

Identified by hardness, rich red hue, and silk-like rutile inclusions. Often found in river gravels (placer deposits) in Myanmar, Sri Lanka, and Thailand.

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