gemstone
Small faceted dark gemstone, possibly spinel or sapphire
Uncertain; candidates include MgAl₂O₄ spinel or corundum (Al₂O₃) sapphire
AI-generated identification · may be incorrectA tiny, polished/faceted, steel-blue to gray stone with bright vitreous reflections and a reddish-brown facet or mounting edge. Spinel hardness is ~7.5–8 Mohs; sapphire is 9; crystal structure cannot be confirmed from the image.
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Physical properties
A tiny, polished/faceted, steel-blue to gray stone with bright vitreous reflections and a reddish-brown facet or mounting edge. Spinel hardness is ~7.5–8 Mohs; sapphire is 9; crystal structure cannot be confirmed from the image.
Formation & geological history
These gemstones crystallize in igneous or metamorphic environments, commonly in marble, basalt-related deposits, or alluvial gravels. Geological ages vary widely by locality, from ancient Precambrian rocks to younger volcanic systems.
Uses & applications
Used primarily in jewelry and collecting; sapphire is also used for durable watch crystals and optical components. The apparent small size and heavy inclusions limit likely gem value.
Geological facts
The image may show a cut stone rather than a natural crystal, and the red-brown perimeter could be a metal setting or coating rather than part of the mineral. Identification requires refractive index, specific gravity, and hardness or spectroscopy testing.
Field identification & locations
Check for uniform faceting, strong dispersion, and absence of bubbles; glass commonly shows rounded bubbles and lower hardness. A jeweler’s loupe, refractometer, and professional gem test are needed for reliable identification.