If you're shopping for diamond-look jewelry without the diamond price, you'll hit two options fast: moissanite and cubic zirconia. They get lumped together constantly. They shouldn't be. One is a real lab-grown gemstone; the other is costume jewelry. Here are the five differences that actually matter.
1. Hardness: One Survives Daily Wear, One Doesn't
Moissanite is a 9.25 on the Mohs hardness scale — second only to diamond (10). Cubic zirconia is an 8–8.5, which sounds close but isn't: household dust contains quartz (7), and anything softer than dust scratches over time. A CZ stone picks up micro-scratches within months and goes cloudy. Moissanite stays sharp-edged and clear for decades.
2. Fire: Moissanite Out-Sparkles Diamond Itself
Moissanite's refractive index (2.65–2.69) is higher than diamond's (2.42), and its dispersion — the rainbow fire you see when light hits it — is more than double. CZ has decent sparkle on day one, but it dulls as the surface scratches and absorbs oils. The fire is the reason people pick iced out moissanite over CZ "iced" pieces: it reads real from across the room.
3. The Diamond Tester
This is the one that settles arguments. Standard thermal diamond testers read heat conductivity — moissanite's is nearly identical to diamond's, so it passes. CZ fails instantly. If a piece needs to hold up to scrutiny, CZ can't. Full breakdown here: Does Moissanite Pass a Diamond Tester?
4. Price: Closer Than You'd Think, for a While
CZ jewelry runs $10–$50. Moissanite runs more — our studs start at $69 and iced cuban chains at $699 — but the comparison isn't one purchase, it's every purchase. CZ pieces get replaced yearly as they cloud. A moissanite piece is bought once. Against diamond, moissanite is still roughly 90% cheaper for the same look. See what moissanite should cost.
5. What It Says on a Certificate
Moissanite (silicon carbide) is graded like a gemstone — ours ships D-color, VVS1-clarity with a certificate of authenticity. CZ has no grading standard because there's nothing to grade; it's a mass-produced simulant. If the listing you're looking at doesn't name the stone, assume CZ.
The Verdict
Buy CZ if the piece is for one night and you'll lose it anyway. Buy moissanite if you want jewelry that tests real, wears daily, and still looks new in ten years. Start with the bestsellers or go straight to the iced out collection.
Moissanite vs CZ: Quick Answers
Can you tell moissanite and CZ apart by eye?
Side by side, yes — moissanite throws more colored fire and holds a sharper polish. A year in, it's obvious: CZ clouds and scratches while moissanite still looks new.
Does cubic zirconia pass a diamond tester?
No. CZ fails a thermal tester immediately. Moissanite passes because its heat conductivity is nearly identical to diamond's.
Why is moissanite more expensive than CZ?
Moissanite is a lab-grown crystal (silicon carbide) that takes real time and energy to grow and cut. CZ is mass-produced by the ton. The durability gap matches the price gap.
Is moissanite just fake diamond?
No — it's its own gemstone with its own chemistry, optics, and grading. It isn't pretending to be diamond; it outperforms it on fire and costs 90% less.
