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Fake Moldavite: How to Tell Real Moldavite From Green Glass

By Digital Towns Crystals · Last reviewed October 8, 2026

Short answer: fake moldavite is green bottle or factory glass, cut or molded to look like the Czech impact glass. The quickest screens are price and size: a large faceted "moldavite" for a few dollars, or any piece with no visible bubbles, is probably glass. Real moldavite shows elongated bubbles, chaotic flow lines and, under a loupe, wire-like lechatelierite, with a deeply etched, sculpted skin. Material called "African moldavite" is not moldavite at all.

What does the price check tell you?

Start with the money, because it filters more fakes than any instrument. Geology.com, whose author is a GIA Graduate Gemologist, bought a faceted green "moldavite" online to see what arrived. In its words, we paid $29.49 for the 13 millimeter x 11 millimeter, 6.19-carat stone, and it turned out to be imitation material. A genuine moldavite of that size would have cost a great deal more, and it would also have been an unusually large cut stone.

That gives two rules worth memorizing, both from the same source: if you are offered a faceted moldavite over two carats, or any moldavite without eye-visible bubbles, there is a good chance it is fake. Supply explains the price floor. Geology.com notes that extensive mining in the Czech Republic has depleted the supply of moldavites, and the International Gem Society records that lapidaries have faceted moldavite gems weighing up to 25 cts, which makes big clean faceted stones rarities, not catalog items.

How is fake moldavite made?

The fakes are older than most buyers think. Faceted moldavite has been set in jewelry since the late 1800s, and once demand outran supply, cutters began faceting "moldavite" from green bottle glass. Later, according to Geology.com, glassmakers in China began manufacturing glass in just the right green color to be deceptively sold as "moldavite", and fake moldavite even made its way into museum collections.

Today's imitations come in three main forms:

  • Faceted green glass: clean, bright, often larger than two carats, with perfectly flat facets and few or no bubbles.
  • Molded "rough": glass poured into molds or tumbled and acid-etched to mimic the sculpted surface. The pattern often repeats, and the edges look rounded and soft rather than sharp and feathery.
  • Mislabeled other glass: honest products such as helenite sold under the wrong name. Geology.com describes helenite as a trade name used for a man-made glass that is produced using volcanic ash from the 1980 eruption of Mount St. Helens, made by heating ash to 2700 degrees Fahrenheit. Its green version is attractive and legitimate under its own name, and a fake when called moldavite.

The point of the distinction: imitation is a disclosed substitute, fake is an undisclosed one. Under the FTC Jewelry Guides, an imitation must be labeled with a word such as "imitation" or "simulated".

How do you check a moldavite step by step?

1. Look for bubbles with the eye, then the loupe

Moldavite cooled from a violent splash of molten rock, so it trapped gas. Geology.com notes that most genuine moldavite contains trapped gas bubbles and flow structures visible at 10x, often to the unaided eye, and that the bubbles are sometimes round but more often elongate, stretched as the glass cooled. Factory glass bubbles, when present, tend to be small, round and few.

2. Read the flow lines

Hold the piece to a light. Real moldavite has a roiled, swirled interior; the IGS compares it to a wavy "heat wave" appearance. Glass made in a furnace and poured into a mold is usually far calmer inside.

3. Hunt for lechatelierite

This is the feature that comes closest to proof without a lab. Lechatelierite is silica glass formed by instantaneous events such as impacts and lightning strikes, and it appears as high-relief grains and wire- or worm-shaped threads. The IGS states that finding lechatelierite inclusions is a strong indication you have a moldavite. Not every piece shows it, so absence is not proof of a fake.

4. Study the surface of rough pieces

Natural moldavite spent millions of years in acidic groundwater, which etched it into feathered, pitted and spiky shapes. Pieces with numerous spines and edges are sometimes called "hedgehogs" in the trade. Molded fakes tend to have smoother pits, uniform texture and a "too neat" outline.

5. Check the color

Genuine moldavite ranges from olive and yellowish green to bottle green, with brownish green in lower grades. Emerald-bright, minty or blue-green glass with perfect clarity is a warning sign.

6. Know the numbers if you can test

Property Moldavite Helenite (man-made green glass)
Mohs hardness 5 to 5.5 5 to 5.5
Specific gravity 2.32 to 2.40 2.3 to 2.4
Refractive index 1.47 to 1.51 typical Varies with the batch
Internal features Elongated bubbles, swirls, lechatelierite Bubble inclusions, calmer interior
Surface (rough) Deeply etched, sharp feathering Cut or tumbled, no natural etching

The moldavite figures are from Geology.com, which also notes that most genuine moldavite has an unusually low refractive index, typically between 1.47 and 1.51, much lower than most minerals and many man-made glasses. The helenite figures, also from Geology.com, show the problem: hardness and density overlap almost exactly with a man-made glass, so they cannot clear a stone on their own. Refractive index needs a refractometer.

What can a gem lab tell you?

When the loupe is inconclusive, laboratory chemistry settles it. The IGS describes two tools. LA-ICP-MS can help distinguish moldavites from "soda-lime" green manufactured glasses, which can have high NaO and CaO content. FTIR spectroscopy shows that moldavites have an asymmetrical absorption peak at 3700 cm⁻¹. Labs also use X-ray luminescence, under which moldavite glows yellow-green. For a high-priced piece or a large cut stone, that testing is the only certainty.

What about obsidian?

Volcanic obsidian overlaps with tektites in color, hardness, density and refractive index, and green obsidian exists. The IGS explains the separation: obsidian contains water, which shows as sharp infrared bands, while tektites won't have these bands because they contain virtually no water. Age helps in the field too: Geology.com notes that obsidian older than a few million years is rare, because volcanic glass is destroyed or altered by weathering, while moldavite has survived about 15 million years. The obsidian guide covers volcanic glass in detail.

What is "African moldavite"?

It is a marketing name, not a mineral. The IGS is direct: no natural moldavites occur in Africa. By definition, only glass from the Nördlinger Ries impact in Germany, about 15 million years ago, can be called moldavite. Africa does produce natural impact glass, notably Libyan desert glass, which the IGS's tektite table lists from Egypt and Libya with a specific gravity of 2.21, a refractive index of 1.462 and a pale greenish yellow color. Most "African moldavite" on the market, though, looks clearer than real moldavite and is probably manufactured glass. The planned moldavite vs Libyan desert glass comparison goes further.

Seller red flags for moldavite

  • Faceted stones over two carats at low prices.
  • Rough with no bubbles, smooth surfaces, or identical shapes across a lot.
  • "African", "Saharan" or "Indonesian" moldavite.
  • No locality beyond "space stone"; good dealers name a Czech area such as South Bohemia, or at least the country.
  • Listings that sell a feeling and never describe the physical piece.

Buying moldavite and other natural glass in the Market

Buy rough moldavite on the evidence you can see: weight in grams, clear photos of both sides, and close-ups that show the etched surface and some internal texture. Small, well-sculpted pieces are normal; big clean ones are not. Examples in stock:

  • Moldavite: small rough pieces, priced as natural material. Check the photos for sharp etching and inclusions, and expect modest size; that is what genuine moldavite looks like at accessible prices. The moldavite guide covers the stone itself.
  • Libyan Desert Glass: the Saharan natural glass, pale yellow rather than green. It is a useful contrast piece and the honest answer to anyone offering "African moldavite".
  • Black Obsidian Crystal Sphere, Polished Volcanic Glass: volcanic rather than impact glass, showing how natural glass looks when polished, with a smooth conchoidal-fracture texture.
  • Rainbow Obsidian: natural volcanic glass with iridescent sheen bands, another genuine glass to compare against green imitations.

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Frequently asked questions

How can I tell if my moldavite is real?

Look for elongated bubbles and swirling flow lines, ideally with a 10x loupe, and for wire-like lechatelierite inclusions. Rough pieces should have deeply etched, feathered surfaces. A large, clean, cheap faceted stone, or any piece without visible bubbles, is probably glass. A lab can confirm with chemistry.

Does real moldavite have bubbles?

Usually, yes. Most genuine moldavite contains gas bubbles, often elongated, visible at 10x and sometimes to the naked eye. Bubbles alone do not prove authenticity, because glass can have them too; their shape, the flow lines around them and lechatelierite matter more.

Is African moldavite real?

No. Moldavite by definition comes only from the strewn field of the Ries impact in Central Europe, mostly the Czech Republic. Africa has other natural glasses, such as Libyan desert glass, but material sold as African moldavite is usually manufactured glass.

Why is real moldavite expensive?

It comes from a limited strewn field, mainly in southern Bohemia, and decades of mining have depleted the supply while demand has grown. Large, well-sculpted pieces and clean faceted stones are scarce, which is why very cheap large pieces are a warning sign.

Is moldavite harder than glass?

Not really. Moldavite is about 5 to 5.5 on the Mohs scale, similar to many man-made glasses. A scratch test will not separate them reliably and risks damaging a real piece, so rely on inclusions, surface texture and, if needed, a lab.

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