gemstone

Blue polished cabochon, likely dyed agate or chalcedony

Chalcedony (microcrystalline quartz, SiO₂); exact material cannot be confirmed from the image

AI-generated identification · may be incorrect

Opaque-to-translucent deep blue, polished vitreous/waxy luster, Mohs hardness about 6.5–7; quartz-family material with no visible cleavage. The uniform color may indicate dye or coating.

Identified September 26, 2026More gemstone →

Explore Blue polished cabochon, likely dyed agate or chalcedony in the encyclopedia →

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Physical properties

Opaque-to-translucent deep blue, polished vitreous/waxy luster, Mohs hardness about 6.5–7; quartz-family material with no visible cleavage. The uniform color may indicate dye or coating.

Formation & geological history

If chalcedony, it formed as silica deposited in cavities or veins, commonly in volcanic rocks; its geological age depends on the deposit. Blue coloration in uniformly colored cabochons is often enhanced by treatment.

Uses & applications

Used in cabochon jewelry and decorative objects. Similar small polished pieces commonly sell for a few dollars.

Geological facts

The oval domed cut is a cabochon, a standard way to show color in opaque or translucent gem material.

Field identification & locations

The photo alone cannot distinguish dyed chalcedony from other blue stones or a non-geological imitation; check for natural banding, inclusions, and hardness, or have it tested. Chalcedony occurs worldwide, including Brazil, India, and the United States.