Moissanite Moe · Nov 11, 2026 · 2 min read
Does Moissanite Pass a Diamond Tester?
Yes. Moissanite passes a standard diamond tester. Most pen testers measure how fast a stone moves heat, and moissanite moves heat almost exactly like a diamond does. Cubic zirconia (CZ) and glass don't, so they fail. Only a dual-mode tester that also checks electrical conductivity can tell moissanite from diamond.
What does a diamond tester actually test?
The tester you see at a pawn shop or jewelry counter is a thermal tester. It touches the stone with a heated tip and measures how quickly heat pulls away from it. Diamond pulls heat away faster than almost anything. The tester beeps when a stone moves heat fast enough to be a diamond.
It does not test for carbon. It does not test for "realness." It tests one physical property.
Why does moissanite pass?
Moissanite (silicon carbide) moves heat about as fast as diamond. On a thermal tester, the two read the same. That's not a trick. It's physics. The same property is why moissanite stays cool to the touch like diamond does.
What fails the tester?
- Cubic zirconia (CZ): fails. Moves heat slowly.
- Glass and crystal: fail.
- White sapphire: usually fails.
- Lab diamond: passes, same as mined diamond.
Most "iced out" jewelry sold online is CZ. That's why it fails at the shop.
Can any tester tell moissanite from diamond?
Yes. A dual tester (thermal plus electrical) can. Moissanite conducts a little electricity; diamond doesn't. Jewelers with a dual tester will flag moissanite. But the handheld pen tester most people own only checks heat, and moissanite passes that every time.
Does the metal matter?
Not for the tester. It only reads the stone. But the metal matters for everything else: brass under thin plating turns skin green, 925 sterling silver doesn't.
FAQ
Does moissanite pass a diamond tester every time?
On a thermal pen tester, yes. On a dual thermal-and-electrical tester, it reads as moissanite.
Is moissanite fake?
No. It's a lab-created gemstone made of silicon carbide, with its own hardness (9.25) and more fire than diamond.
Can I test it myself?
Yes. A basic pen tester costs about $15 online. Ours pass.
Why does my chain fail the tester?
It's almost certainly CZ or glass. Moissanite would pass.
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