mineral

Blue Sapphire (likely costume glass imitation)

Corundum (Al2O3) with iron/titanium impurities

Hardness: 9 (Mohs scale), Color: Sky blue to deep navy, Luster: Vitreous/Adamantine, Crystal structure: Trigonal (hexagonal prisms), SG: 3.95-4.03

Identified March 14, 2026More mineral →

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Physical properties

Hardness: 9 (Mohs scale), Color: Sky blue to deep navy, Luster: Vitreous/Adamantine, Crystal structure: Trigonal (hexagonal prisms), SG: 3.95-4.03

Formation & geological history

Formed in metamorphic rocks like marble or schist, and in igneous rocks like basalt. Crystallization occurs under high pressure/temperature over millions of years.

Uses & applications

High-end jewelry, industrial abrasives, watch crystals, and laser components (synthetic versions).

Geological facts

Sapphires are the second hardest natural mineral after diamond. Most natural blue sapphires are heat-treated to enhance their color and clarity for the market.

Field identification & locations

Field identification involves checking for 6-sided crystal shapes and superior hardness. This specimen appears to be vintage costume jewelry, likely using faceted blue glass or leaded crystal rather than natural gems.

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