gemstone

Likely amethyst cabochon ring

Quartz, SiO₂; purple coloration from trace iron and irradiation

AI-generated identification · may be incorrect

The image shows a polished, opaque-to-translucent purple cabochon in a silver-colored setting. Quartz has Mohs hardness 7, vitreous luster, hexagonal crystal structure, no cleavage, and specific gravity about 2.65; the stone’s exact identity cannot be confirmed visually.

Identified September 14, 2026More gemstone →

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Physical properties

Formation & geological history

Amethyst forms in silica-rich cavities of volcanic rocks, especially basaltic lava flows, when iron-bearing quartz is irradiated during growth. Most gem amethyst formed in Phanerozoic volcanic settings, commonly tens to hundreds of millions of years old.

Uses & applications

Used in jewelry, carvings, mineral specimens, and occasionally industrial quartz applications. Value depends heavily on color, transparency, size, cut, and whether the setting is sterling silver.

Geological facts

High-quality amethyst is saturated violet with reddish flashes; very dark or grayish stones are generally less valuable. Heat treatment can produce citrine-like colors, while glass and synthetic quartz are common imitations.

Field identification & locations

Check for quartz-like hardness, natural color zoning, inclusions, and refractive doubling; definitive identification requires gemological testing. Major sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico.