Moldavite
Last updated: April 2026
Tektite — natural glass formed ~14.8 million years ago by a meteorite impact in the Ries crater (Germany), with ejected melt landing in what is now the Czech Republic. The only gem-quality tektite. Heavily faked with manufactured green glass; genuine moldavite has lechatelierite inclusions and sculptured surface texture.
Physical & Optical Properties
RI Range1.480–1.510
SG Range2.32–2.38
SG Typical2.35
Hardness (Mohs)5.5
Crystal SystemAmorphous
Optic CharacterSR (Singly Refractive)
Dispersion0.010
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsGreen
SpeciesSilica Glass (tektite)
Key Differentiators
- Unique sculptured/etched exterior surface with flow ridges, pitting, and corrosion features
- Lechatelierite inclusions — wispy pure SiO₂ glass threads unique to tektites, absent in man-made glass
- Low SG 2.32–2.38 — lighter than most glass fakes (~2.40+) and most other green stones
- Found ONLY in Bohemia/Moravia (Czech Republic) — any 'moldavite' from elsewhere is fake
- Flow structures (schlieren) and gas bubbles under loupe — no crystalline inclusions possible
Common Simulants
- Manufactured Green Glass: Green glass fakes lack lechatelierite inclusions. Glass fakes typically have higher SG (2.40+), may show mold seams, and lack the organic sculptured surface corrosion of genuine moldavite. Look for lechatelierite under 20–40× magnification — its presence indicates genuine moldavite.
- Green Tourmaline: Tourmaline is crystalline (doubly refractive), RI 1.624–1.644, much higher than moldavite glass (1.48–1.51). SG 3.06. Not isotropic.
- Green Sapphire: Sapphire RI 1.762–1.778 is far higher than moldavite. SG 3.99–4.05. Not comparable on any standard test.
Price Context
Natural — low ($/ct)$20
Natural — high ($/ct)$500
NotePer carat or per gram for rough; $20–80/ct for typical faceted material; $100–500+ for large (10+ ct), museum-quality, deeply sculptured natural pieces; market flooded with fakes so authentication is essential
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a moldavite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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