mineral

Ruby

Corundum (Al2O3 with Chromium traces)

Hardness: 9 on Mohs scale; Color: Pinkish-red to pigeon-blood red; Luster: Vitreous to sub-adamantine; Crystal structure: Trigonal (Hexagonal system); Cleavage: None; Specific gravity: 3.97-4.05

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

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale; Color: Pinkish-red to pigeon-blood red; Luster: Vitreous to sub-adamantine; Crystal structure: Trigonal (Hexagonal system); Cleavage: None; Specific gravity: 3.97-4.05

Formation & geological history

Formed in metamorphic rocks (marble or schist) or igneous environments (basalt) via intense heat and pressure. Most high-quality rubies formed during the collision of tectonic plates millions of years ago, specifically the Tertiary period for most Asian deposits.

Uses & applications

Primary use is in high-end jewelry (rings, necklaces, earrings). Industrially, synthetic rubies are used in lasers, watch bearings, and specialized high-pressure surgical tools.

Geological facts

Ruby is the birthstone for July. The red color is caused by the element chromium; without it, the mineral would be a sapphire. The most valuable rubies exhibit a 'pigeon blood' red hue with a hint of violet.

Field identification & locations

Identify by its extreme hardness (scratched only by diamond) and characteristic hexagonal crystal habit in the field. Often found in alluvial deposits (river beds) or marble outcrops in regions like Myanmar, Sri Lanka, and Madagascar.