Carnelian
Last updated: April 2026
Orange-red to red-brown translucent chalcedony; color from iron oxide (hematite/goethite). Carnelian is lighter and more orange than sard (darker brown-red). Heat treatment of brown agate to produce carnelian is a traditional and accepted practice. Dyeing is also common; color concentrated in surface fissures under loupe is a detection indicator. Modern commercial carnelian is often dyed agate.
Physical & Optical Properties
RI Range1.530–1.543
SG Range2.58–2.64
SG Typical2.61
Hardness (Mohs)6.5–7
Crystal SystemTrigonal
Optic CharacterAggregate
Dispersion0.013
Fluorescence LWWeak white/cream
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsRed Pink, Yellow Orange
SpeciesQuartz
Related: Quartz Varieties
Key Differentiators
- Translucent orange-red to red-brown body color — primary identifier
- Waxy luster; even color distribution (uniform, not banded)
- Holds light from within when backlit — thin edges show translucency
- Distinguish from sard by lighter, more orange color (sard is darker brown)
- Distinguish from red jasper by translucency (jasper is fully opaque)
- Heat treatment from brown agate to bright carnelian is traditional and expected
Common Simulants
- Red/orange glass: Isotropic; gas bubbles; lower SG; no waxy luster.
- Red jasper: Fully opaque; same species but jasper contains up to 20% other minerals; lacks translucency of carnelian.
Treatments
- Heat Treatment (traditional — agate heated to produce/brighten orange-red; widely accepted)
- Dyed (common — color in fissures under 10×; acetone test)
Price Context
Natural — low ($/ct)$1
Natural — high ($/ct)$30
NotePer carat; common commercial carnelian is $1–5/ct; fine translucent natural carnelian $10–30/ct
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a carnelian? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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