Yes, on most standard diamond testers. Moissanite conducts heat almost like diamond, so a thermal tester reads it as diamond, and Mariqe's stones pass the diamond test. An electrical conductivity tester or a moissanite-specific tester will identify it as moissanite. A diamond tester alone cannot prove that a stone is diamond.
How diamond testers work
Most handheld diamond testers, the pen-style ones a jeweller keeps at the counter, measure thermal conductivity. Diamond moves heat away from the probe tip very quickly, and the tester reads that as diamond. This works well for telling diamond from most imitations, because most imitations conduct heat poorly.
Moissanite is the exception. Its thermal conductivity is close enough to diamond's that testing equipment based on heat gives a diamond-like result. That is a property of the material, not a trick, and it is why a basic thermal tester cannot separate the two.
What each test says about moissanite
| Test | Result on moissanite |
|---|---|
| Thermal conductivity tester (the common pen-style tester) | Reads as diamond |
| Electrical conductivity tester | Shows higher conductivity for moissanite, so it can be told apart from diamond |
| Moissanite tester or multi-tester with a moissanite mode | Identifies it as moissanite |
| Magnification by a trained jeweller | Doubled facet edges can be visible, because moissanite is doubly refractive and diamond is not |
Reference sources describe electrical conductivity as the more practical way to separate moissanite from diamond. Testers that check for both heat and electrical conductivity are available, and they are the ones to trust if the answer matters.
What "passes the diamond test" does and does not mean
It means a basic thermal tester reads the stone as diamond. It does not mean the stone is diamond. Moissanite is silicon carbide and diamond is carbon. They are different gemstones, and Mariqe sells moissanite as moissanite.
That matters because a tester result is easy to over-read. A ring that reads as diamond on a pen tester is still moissanite, and if someone asks what it is, the honest answer is the simple one. We cover that conversation in what to say when someone asks if it is real.
What about cubic zirconia?
Cubic zirconia behaves the opposite way. It is a thermal insulator, while diamond is a strong thermal conductor, and that difference is the basis of the standard method for telling the two apart. A thermal diamond tester therefore reads cubic zirconia as not diamond, while it reads moissanite as diamond. If you are comparing moissanite with cubic zirconia, the tester is one of the clearest practical differences between them.
What if a jeweller says it is moissanite?
That is the correct answer for a moissanite ring, and there is nothing wrong with your piece. Jewellers who use a moissanite-aware tester at a repair or an appraisal will see it. What matters is that you know what you bought, which is why we state the material plainly on every product page: D colour, VVS1 clarity, excellent cut, Mariqe moissanite.
If a test of a Mariqe stone ever gives you a result you did not expect, email service@mariqe.com and we will look into it with you.
When a tester result matters
It matters most when you are buying or selling a stone described as diamond. If a listing says diamond and the only evidence is a reading from a thermal pen, moissanite has not been ruled out. Ask for a report from a recognised laboratory, or have the stone checked with a tester that includes a moissanite or electrical conductivity mode.
It matters in a smaller way if you own moissanite. Describe the piece accurately when you insure it or take it for repair, so the record matches what it is. A jeweller who tests it with a moissanite-aware tester will simply confirm that.
Where moissanite differs from diamond
A tester result is one property. The others are different. Moissanite has a refractive index of 2.65 against diamond's 2.42, and it is doubly refractive where diamond is not. Its hardness is 9.25 on the Mohs scale against diamond's 10, so diamond is the harder stone. Its density is about 3.22 grams per cubic centimetre. Each of these separates it from diamond, and together they make it a gemstone in its own right: more fire than diamond, slightly less hardness, and a different material.
What this means for you
A pen tester is a quick check, not proof. If you want to confirm what a stone is, use a tester that checks electrical conductivity or a moissanite mode, or ask a gemmologist. If you own moissanite, expect a thermal tester to read it as diamond, and know that a more advanced test will not. Enjoy it for what it is.
Eterna Stud Earrings
Six-prong round moissanite studs, D colour and VVS1 clarity, in 925 sterling silver with platinum or 18k gold plating. Choose 6.5mm, 8mm or 9.1mm. From $88 a pair, with a Lifetime Moissanite Warranty.
See sizes and pricesFrequently asked questions
Does moissanite pass a diamond tester?
It passes a standard thermal diamond tester, which reads it as diamond. An electrical conductivity tester or a moissanite-specific tester identifies it as moissanite.
Can a jeweller tell moissanite from diamond?
Yes. A jeweller with a tester that checks electrical conductivity or has a moissanite mode can tell them apart, and magnification can show the doubled facet edges that moissanite's double refraction produces.
Does cubic zirconia pass a diamond tester?
No. Cubic zirconia is a thermal insulator, so a thermal diamond tester reads it as not diamond. Moissanite reads as diamond on the same tester.
Is passing the diamond test the same as being a diamond?
No. Passing a thermal diamond test means the stone conducts heat like diamond. Moissanite does, but it is silicon carbide, not carbon, and it is a different gemstone from diamond.