gemstone

Polished blue-purple chalcedony (likely dyed or coated)

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent blue-violet color, vitreous to waxy luster, cryptocrystalline structure, no visible cleavage, specific gravity about 2.60. The unusually uniform color and strong surface sheen suggest treatment; it may be marketed as “blue chalcedony” or “opalescent chalcedony.”

Identified September 11, 2026More gemstone →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich fluids fill cavities and fractures, commonly in volcanic rocks, depositing microscopic quartz fibers. It formed over geological timescales, generally from Paleozoic to Cenozoic host rocks depending on locality.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; treated material is mainly a decorative gemstone. Untreated fine blue chalcedony is more collectible.

Geological facts

Its color may result from trace elements, microscopic inclusions, irradiation, dye, or surface coating. A natural blue chalcedony cabochon typically has more uneven color zoning than this specimen.

Field identification & locations

Common sources include Turkey, Namibia, Indonesia, Brazil, India, and the United States. Check for dye concentration in cracks, acetone transfer, scratches, and coating wear; a gemological test is needed for definitive identification.