gemstone

Blue Sapphire

Corundum (Al2O3 with Cr, Fe, and Ti trace elements)

Hardness: 9 (Mohs scale); Color: Deep velvet blue; Luster: Vitreous to Adamantine; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.95-4.03

Hardness: 9 (Mohs scale)
Color: Deep velvet blue
Luster: Vitreous to Adamantine

Identified July 17, 2026More gemstone →

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Physical properties

Hardness: 9 (Mohs scale); Color: Deep velvet blue; Luster: Vitreous to Adamantine; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.95-4.03

Formation & geological history

Formed in metamorphic rocks seperti marble or basaltic rocks under high pressure and temperature. Primary sources include alluvial gravel deposits.

Uses & applications

Primarily used in high-end jewelry (rings, earrings), and industrial applications like scratch-resistant watch crystals and optical components due to extreme hardness.

Geological facts

Sapphire is the birthstone for September and is the second hardest natural mineral after diamond. The blue color is due to the presence of titanium and iron.

Field identification & locations

Look for its characteristic 'velvety' blue glow. In the field, it is often found in river beds (alluvial deposits). Professional lab testing is required to distinguish natural from synthetic lab-grown corundum.

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