Does Moissanite Pass the Diamond Tester

Q: "Will it pass?"

Short answer: Yes—most standard diamond testers will say your Moissanite IS a diamond.

Q: Does "Passing" Make It a Fake Diamond?

No. And this is important: - Moissanite is NOT diamond. - Moissanite is Silicon Carbide (SiC) — a naturally occurring mineral, now lab-grown. - It has higher refractive fire(rainbow sparkle) than diamond. - Passing a tester is a physical property, not a claim of being mined diamond.

Kevin Lin
3 days ago
2 min read

Updated: 2 hours ago

If you’re dropping money on an Iced Out Cuban Link or a VVS Moissanite pendant, this is probably the first question on your mind:

"Will it pass?"

Short answer: Yes—most standard diamond testers will say your Moissanite IS a diamond.

But the full answer is more nuanced, and knowing it protects you from scams and bad information.

How a Diamond Tester Actually Works

Most jewelers and pawn shops use a thermal conductivity tester. Here’s what it does:

The probe heats up slightly.
It touches the stone.
It measures how fast heat dissipates through the gem.
Diamond: Dissipates heat very quickly → Tester beeps = "Diamond"
Moissanite: Also dissipates heat very quickly → Tester beeps = "Diamond"
Cubic Zirconia (CZ) / Glass / Plastic: Poor heat conductors → No beep

👉 Moissanite (Silicon Carbide) has thermal conductivity extremely close to diamond, which is why it passes standard testers.

So Why Do Some Say It "Fails"?

Two reasons:

1. You’re Using a Cheap $10 Tester

Low-end testers sometimes have a narrow calibration range. They can false-negative on larger Moissanite stones (especially 6mm+), not because it’s "fake," but because the device can’t differentiate the slightly different thermal curve.

2. Confusion with CZ

CZ never passes a thermal tester. If someone tells you "Moissanite failed," ask: Was it actually Moissanite, or was it CZ with silver stamping?

The Pro Way: Electrical Conductivity Testers

High-end jewelers use a dual tester (thermal + electrical conductivity):

Diamond: Thermal = pass, Electrical = no reaction
Moissanite: Thermal = pass, Electrical = reacts (Moissanite conducts electricity; diamond does not)
CZ: Fails thermal

This is how pros tell them apart. We encourage customers to test theirs—we have nothing to hide.

Does "Passing" Make It a Fake Diamond?

No. And this is important:

Moissanite is NOT diamond.
Moissanite is Silicon Carbide (SiC) — a naturally occurring mineral, now lab-grown.
It has higher refractive fire(rainbow sparkle) than diamond.
Passing a tester is a physical property, not a claim of being mined diamond.

If a seller tells you "It passed so it must be a real diamond," they either don’t know gems or are lying.

If a seller says "It passes because it's high-quality Moissanite," that’s the truth.

Why This Matters for Hip Hop Jewelry

In the Hip Hop world, ice is about visual impact, not geological origin.

You want:

✅ Stones that look wet and icy under light
✅ Stones that pass casual inspection / tester
✅ A base metal that won’t turn your neck green (925 Silver ✅)

Moissanite delivers all three—without the $10,000+ price tag of a diamond Cuban.

The GLEEI Bottom Line

✅ Yes, Moissanite passes standard diamond testers.
✅ It will not pass a true electrical conductivity test (used by gem labs, not street-level checks).
✅ CZ will not pass thermal testers.
✅ All GLEEI VVS Moissanite pieces are lab-grown SiC and tested before setting.