How to Spot Fake Moissanite
The usual fake is not a clever fake. It is a cubic zirconia in a moissanite box, sold by someone counting on you never measuring the stone or looking through a loupe. Three checks catch nearly all of them.
What "fake moissanite" usually means
Nobody counterfeits silicon carbide by making silicon carbide badly. The substitute is cubic zirconia — furnace-grown zirconium dioxide, hardness 8–8.5, cheap in any size, and convincing in a photograph. It gets sold as moissanite because the price difference is large. Occasionally white sapphire or glass appears instead, but CZ is the standard swap.
Start with calipers
Measure the stone across its girdle in millimetres and compare that number to what you were sold. It catches a surprising number of substitutions, for two reasons.
First, CZ and moissanite have very different densities. Zirconium dioxide is roughly 5.6 to 6 specific gravity; moissanite is about 3.2. So a CZ cut to the same diameter weighs nearly twice what the moissanite should. If a seller quotes you carat weight rather than millimetres, and the stone weighs far more than its diameter implies, you are not holding moissanite.
Second, honest listings quote diameter because that is what you see: a 6.5 mm stone is 6.5 mm regardless of material, while "one carat" is not. If the diameter on the card and the diameter under the calipers disagree by more than a tenth of a millimetre, the card is not describing that stone.
The doubling test is the real evidence
This is the one test that speaks directly to what the material is. Moissanite is birefringent: light entering the stone splits into two rays, so every facet edge at the back of the stone appears twice. CZ, white sapphire and glass are singly refractive and show one clean edge.
Two ways to see it. With a 10x loupe, look down through the table at the sharp junctions where the pavilion facets meet. On moissanite those junctions look slightly blurred or doubled. On CZ they are crisp single lines.
Without a loupe, use the print test. Lay the stone table-down on newsprint or any fine text and look at it from directly above. A moissanite doubles the letters into two overlapping images; a CZ shows one readable image through the stone. It takes ten seconds, needs no equipment, and strong direct light makes it easiest to see.
Why a thermal tester will not help
Diamond testers measure heat conduction. Diamond conducts heat extremely well, CZ conducts it poorly, and the tool was built to separate those two. The problem is that silicon carbide also conducts heat very well — well enough that a simple thermal tester reads moissanite as diamond. So the instrument answers a question you did not ask, and a "passes the diamond tester" claim tells you nothing about whether the stone is moissanite or CZ.
Multifunction testers with a moissanite setting exist and can be useful in trained hands, but consumer units are inconsistent. Refractometer readings and a jeweller's loupe are worth more than a gadget with three coloured lights.
Match the card to the stone
A GRA card is not proof of authenticity on its own; it is a description, and cards are easy to reprint. What makes it useful is that it carries measurements, so you can check whether the paper and the stone are the same object.
Do three things. Read the diameter on the card and measure the stone — they should agree to a tenth of a millimetre. Check that the colour and clarity grades on the card match what the listing claimed, since "GRA" alone says nothing about grade. And check the card came with the specific piece you ordered, not a generic card for the model — one that could belong to any stone in the batch is a leaflet, not a record.
What the certificate does and does not prove
| Check | What it proves | What it misses |
| Calipers | Size matches the listing; weight is plausible for the material | Colour and clarity grades |
| Doubling test | The stone is birefringent — i.e. silicon carbide family | Which grade of moissanite |
| Thermal tester | Roughly nothing, on this question | Distinguishing moissanite from diamond |
| GRA card | Stated grade and measurements, if matched to the stone | That the stone in your hand is that stone |
Buying so you do not have to test
The fastest defence is a seller who states the material in one line, quotes a diameter in millimetres, names the grade, and ships a GRA card that matches the stone. If any of those is missing, ask before you pay. A seller who cannot say "silicon carbide, GRA D colour VVS1, 6.5 mm" is either confused about their own product or hoping you are.
And if you already own a piece you are unsure about, take it to any jeweller with a loupe and ask them to look for doubling. It is a two-minute favour, and it settles the question better than any consumer device.
What we make
Our factory in Guangxi has been producing since 2008. Every moissanite piece we sell is GRA D colour, VVS1, in 925 sterling silver, 9K, 14K or 18K gold, and the card that ships with it lists the measurements you can check with calipers on arrival. Lab grown diamonds in our range carry IGI reports instead — different material, different paperwork, no overlap.
Prices run from $17 to $2,020 with a median around $98. Free shipping over $99, $5.99 under that, and 30 days to return anything unworn in its original packaging — long enough to have the stone looked at by someone with a loupe before you commit.
