Whether you’ve just received a moissanite ring or you’re evaluating a second-hand piece, knowing how to verify your stone’s authenticity is straightforward when you know what to test. Here are five methods — from at-home observation to professional testing — ordered from simplest to most definitive.
Test 1: GRA Certificate Verification (Most Definitive)
The most reliable proof of moissanite authenticity is a valid GRA (Gemological Research Association) certificate with a verifiable certificate number. Every Moissanite Shine stone ships with a GRA certificate that includes: the stone’s identity (moissanite/silicon carbide), color grade (DEF, GH, etc.), clarity grade (VVS1, etc.), carat weight, cut grade, and a unique certificate number.
To verify: visit the GRA website and enter your certificate number. The certificate in your hand should match the certificate on record exactly — same stone specifications, same certificate number. Any discrepancy warrants further investigation.
If your stone does not have a GRA certificate, that doesn’t automatically mean it’s not moissanite — but it means you have no independent documentation of its identity. The remaining tests can help assess the stone physically.
Read: How to Verify Your GRA Certificate.
Test 2: Thermal Conductivity Tester
Standard diamond testers measure thermal conductivity — how quickly heat passes through a material. Moissanite’s thermal conductivity (490 W/m·K) is high enough that it passes standard thermal diamond tests, reading as “diamond” or “high conductivity.”
This test confirms the stone is not glass (thermal conductivity ~1 W/m·K) or cubic zirconia (~2 W/m·K). A stone that fails a thermal conductivity test is not moissanite — it is likely glass, CZ, or another simulant.
To distinguish moissanite from diamond definitively, a dual-mode tester is needed. Read: Why Moissanite Passes Diamond Testers.
Test 3: Electrical Conductivity (Moissanite-Specific Test)
Moissanite is a semiconductor — it conducts small amounts of electricity in a way that diamond does not. Dual-mode testers (available for $30–$80 online) measure both thermal and electrical conductivity. A stone that shows high thermal conductivity AND electrical conductivity is moissanite, not diamond.
This is the standard professional test for distinguishing moissanite from diamond. If your stone passes both tests, it is moissanite. If it passes thermal but not electrical, it may be diamond or a different high-conductivity stone.
Test 4: Loupe Examination — Double Refraction
Moissanite is birefringent (doubly refractive). When viewed through a 10x jeweler’s loupe from the side (through the pavilion facets), you can see doubled facet edges — each facet appears to have a shadow or double image behind it. This effect is visible under magnification in specific viewing orientations.
Diamond is isotropic (singly refractive) and does not show this doubling effect. CZ is also isotropic. White sapphire, zircon, and topaz show varying degrees of birefringence but with different visual characteristics than moissanite.
This test requires a 10x loupe and some practice — it’s most reliable for experienced observers, but it is a genuine distinguishing characteristic of moissanite.
Test 5: Scratch Test (Elimination Test)
Moissanite has a Mohs hardness of 9.25. It will scratch glass (5.5 Mohs), steel (6.5–7.5 Mohs), and most common materials. It will not be scratched by them.
This is an elimination test, not a positive identification test: a stone that scratches easily is not moissanite. A stone that scratches glass and resists scratching from steel could be moissanite, diamond, ruby, sapphire, or another hard stone — further testing is needed to narrow it down.
Caution: Never use a scratch test on a mounted stone — the metal setting will scratch easily regardless of the stone’s hardness, creating confusion. And never scratch your stone against another piece of jewelry you care about.
What a Professional Jeweler Can Do
If you need definitive identification, take the stone to a gemologist or a jeweler with a Presidium or similar multi-tester instrument. A combination of thermal conductivity, electrical conductivity, refractive index measurement, and visual examination under magnification will definitively identify any stone.
GIA, IGI, and other major gemological laboratories also offer stone identification services if you need fully documented identification for insurance or legal purposes.
The Simplest Assurance
If you purchase from Moissanite Shine, your stone arrives with a GRA certificate, a verifiable certificate number, and our Lifetime Gemstone Warranty. The documentation exists before you need to test anything. Verification is a certificate number check away.
Browse our engagement ring collection or best-selling jewelry — all DEF color, VVS1 clarity, GRA-certified.
🛡️ Lifetime Gemstone Warranty — Your stones are protected forever.
⬆️ Lifetime Upgrade Program — Upgrade your stones or metal anytime.
✏️ Request a Custom Design — Make it uniquely yours.
Related guides:
GRA Certificate Verification Guide
Why Moissanite Passes Diamond Testers
Moissanite Birefringence Explained
Does Moissanite Pass a Diamond Tester?