Chalcedony
Microcrystalline quartz aggregate. Generic chalcedony is translucent blue, grey, or white. Varieties include Agate (banded), Carnelian (orange-red), Onyx (black), Chrysoprase (apple-green), and Bloodstone (dark green with red spots) — each listed as a separate entry. RI reads as a single spot (~1.535) due to aggregate structure.
Physical & Optical Properties
Related: Quartz Varieties
Key Differentiators
- Microcrystalline quartz aggregate — RI ~1.535 lower than macrocrystalline quartz (1.544–1.553)
- Waxy luster (rarely vitreous)
- No facet doubling visible under loupe
- Hardness 6.5–7 — scratches glass
- See specific variety entries: Agate, Carnelian, Onyx, Chrysoprase, Bloodstone
Treatments
- Dyed (very common — carnelian, onyx, chrysoprase)
- Heat Treatment (carnelian brightened from agate)
- Imitation (glass, plastic)
Price Context
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
About Chalcedony
Microcrystalline quartz aggregate. Generic chalcedony is translucent blue, grey, or white. Varieties include Agate (banded), Carnelian (orange-red), Onyx (black), Chrysoprase (apple-green), and Bloodstone (dark green with red spots) — each listed as a separate entry. RI reads as a single spot (~1.535) due to aggregate structure.
Identifying a chalcedony? GemID walks through these tests in order — RI, SG, fluorescence, and more.
Try GemID Free →