gemstone

Polished red chalcedony (likely dyed agate)

Chalcedony, microcrystalline quartz (SiO₂), possibly colored by iron oxides or dye

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent to opaque red with a waxy-to-glassy luster, cryptocrystalline structure, and no visible cleavage. The smooth, polished surface and possible banding are typical of agate/chalcedony.

Identified September 20, 2026More gemstone →

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At a glance

Common name: Polished red chalcedony (likely dyed agate)
Scientific name: Chalcedony, microcrystalline quartz (SiO₂), possibly colored by iron oxides or dye
Category: gemstone
Identified: September 20, 2026
Method: Standard

AI Estimated Value

Approximately $10–$75 for a common polished piece; $100–$300+ if large, naturally colored, well-banded, and demonstrably untreated.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing successive layers of microcrystalline quartz over millions of years, commonly during the Cenozoic or older volcanic episodes. Strong uniform red color may indicate human dyeing or enhancement.

Uses & applications

Used for cabochons, carvings, ornamental slabs, jewelry, and decorative objects; common polished pieces have modest collector value.

Geological facts

Chalcedony is quartz whose crystals are too small to see unaided; agate is a banded variety. Dye concentrations in cracks, pores, or along edges can distinguish treated material from naturally colored stone.

Field identification & locations

Common sources include Brazil, Uruguay, India, Madagascar, Mexico, and the United States. Test with a loupe for curved or parallel banding, inspect color concentration at fractures, and avoid acid or scratch testing on the polished face.