Coral
An organic gemstone formed from the skeletal remains of marine polyps.
Physical & Optical Properties
RI Range1.486–1.658
SG Range2.60–2.70
SG Typical2.68
Hardness (Mohs)3–4
Crystal SystemAggregate
Optic CharacterAggregate
Dispersion0.000
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsRed Pink, Colorless, Black, Blue Violet
SpeciesOrganic
Related: Organic Varieties
Key Differentiators
- Organic origin (skeletal material)
- Often shows a wood-grain like structure
- Effervesces in acid
Treatments
- Bleaching (to whiten)
- Dyeing (to redden or deepen color)
- Imitation (plastic, dyed bone, dyed howlite)
Price Context
Natural — low ($/ct)$10
Natural — high ($/ct)$200
NotePer piece (not per carat); ox-blood red coral commands highest prices; CITES restrictions apply
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
About Coral
An organic gemstone formed from the skeletal remains of marine polyps.
Identifying a coral? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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