Zircon
A brilliant natural gemstone with high dispersion, not to be confused with cubic zirconia.
Physical & Optical Properties
RI Range1.925–1.984
SG Range4.60–4.80
SG Typical4.69
Hardness (Mohs)7.5
Crystal SystemTetragonal
Optic CharacterDR Uniaxial (+)
Birefringence0.059
Dispersion0.039
Fluorescence LWOrange
Fluorescence SWInert
Chelsea FilterInert
PleochroismModerate
ColorsBlue Violet, Brown, Green, Yellow Orange, Red Pink, Colorless
SpeciesZircon
Related: Zircon Varieties
Key Differentiators
- Extreme facet doubling
- Adamantine luster
- High RI, SG, and dispersion
Common Simulants
- Diamond: Diamond: isotropic (SR) — no doubling; thermal probe reads hot; RI 2.42; SG 3.52; extreme hardness (10).
- Blue sapphire: Sapphire: uniaxial negative; RI 1.762–1.778; SG 4.00; much lower birefringence (no strong doubling).
- Spinel: Spinel: isotropic; no doubling; RI ~1.718; SG ~3.60.
- Tanzanite: Tanzanite: biaxial positive; lower SG (3.35); no strong doubling; RI 1.691–1.700; trichroic.
Commonly Confused With
Commonly confused with: Diamond, Sapphire, Spinel, Tanzanite, Chrysoberyl, Cubic Zirconia, Demantoid Garnet.
Treatments
- Heat Treatment (to colorless or blue)
Price Context
Natural — low ($/ct)$50
Natural — high ($/ct)$300
NotePer carat; heat-treated blue most common; red and green natural-color are rarer and higher
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
About Zircon
A brilliant natural gemstone with high dispersion, not to be confused with cubic zirconia.
Identifying a zircon? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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