Rock Identifier
Blue faceted gemstones, likely blue sapphire (Corundum (Al₂O₃), blue varieties colored chiefly by iron and titanium) — gemstone
gemstone

Blue faceted gemstones, likely blue sapphire

Corundum (Al₂O₃), blue varieties colored chiefly by iron and titanium

AI-generated identification · may be incorrect

Hardness 9 Mohs; typically blue, vitreous luster, trigonal crystal structure, and no prominent cleavage. The pictured small faceted stones may also be blue spinel or synthetic sapphire; the image alone cannot confirm identity.

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Physical properties

Hardness 9 Mohs; typically blue, vitreous luster, trigonal crystal structure, and no prominent cleavage. The pictured small faceted stones may also be blue spinel or synthetic sapphire; the image alone cannot confirm identity.

Formation & geological history

Natural sapphire forms in aluminum-rich metamorphic rocks or certain igneous deposits, commonly during regional metamorphism; geological ages vary widely. Synthetic stones are laboratory-grown and may be nearly identical visually.

Uses & applications

Used extensively in jewelry, watches, and precision components; industrial sapphire serves as scratch-resistant windows and bearings.

Geological facts

Sapphire is the non-red gem variety of corundum; ruby is also corundum but colored mainly by chromium. Strong pleochroism, inclusions, and laboratory testing help distinguish natural stones from synthetics and imitations.

Field identification & locations

Field identification requires hardness, refractive index, specific gravity, dichroscope, and microscopy; color alone is insufficient. Major sources include Sri Lanka, Myanmar, Kashmir, Madagascar, Australia, and Montana.