Rock Identifier
Faceted gemstones, likely mixed small sapphires or spinel (Corundum (Al₂O₃) or spinel (MgAl₂O₄); exact identification requires testing) — gemstone
gemstone

Faceted gemstones, likely mixed small sapphires or spinel

Corundum (Al₂O₃) or spinel (MgAl₂O₄); exact identification requires testing

AI-generated identification · may be incorrect

Small transparent-to-translucent faceted stones with vitreous luster, gray-blue to purplish and colorless tones. Sapphire hardness is Mohs 9; spinel is Mohs 8; both have nonmetallic luster and distinct crystal structures.

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Physical properties

Small transparent-to-translucent faceted stones with vitreous luster, gray-blue to purplish and colorless tones. Sapphire hardness is Mohs 9; spinel is Mohs 8; both have nonmetallic luster and distinct crystal structures.

Formation & geological history

Natural corundum and spinel crystallize in metamorphic rocks and some igneous deposits, commonly in marble, schist, or placer gravels. Geological ages vary widely, generally millions to billions of years.

Uses & applications

Used as jewelry gemstones and collector specimens; sapphire is also used industrially for scratch-resistant windows and abrasives.

Geological facts

The photograph shows multiple cut stones mounted or displayed on a board, not a single rock specimen. Color and faceting alone cannot reliably distinguish sapphire from spinel or glass.

Field identification & locations

Check refractive index, birefringence, inclusions, and hardness; a gemological loupe and refractometer are useful, while scratch testing may damage them. Common sources include Sri Lanka, Myanmar, Madagascar, Tanzania, and Vietnam.