Key Takeaways

• Thermal testers usually read moissanite as diamond.
• Electrical conductivity testers can identify moissanite.
• Moissanite is doubly refractive; diamond is singly refractive.

It is one of the most common questions we hear: will moissanite pass a diamond tester? The short answer is that it passes most standard testers. Here is the full, honest explanation.

How Diamond Testers Work

There are two main types of handheld tester:

• Thermal testers measure how quickly heat moves through a stone. Diamond conducts heat extremely well, so these testers look for that fast heat flow.
• Electrical conductivity testers measure whether a stone conducts a small electric current. Diamond does not; moissanite does.

Why Moissanite Passes Thermal Testers

Moissanite conducts heat almost as well as diamond. On a standard thermal tester, the most common type, moissanite reads as diamond. This is one reason moissanite is so often mistaken for diamond, even by experienced eyes.

Which Testers Can Tell the Difference?

Many newer testers combine a thermal probe with an electrical conductivity check, often labeled as a "multi-tester" or "moissanite tester". These can identify moissanite. Professional gem labs can also tell the two apart using magnification and specialized equipment.

How Else Can Moissanite Be Identified?

Moissanite is doubly refractive, meaning light splits into two rays as it passes through. Under magnification, and from some angles, this can make the back facets look slightly doubled. Well-cut stones are oriented to minimize this, so it is very hard to see with the naked eye.

What This Means for You

Moissanite is not trying to be something it is not. It is a genuine gemstone with its own brilliant character, and we always sell it openly as moissanite. The fact that it passes most diamond testers simply shows how remarkably close it is to diamond in look and feel, at a fraction of the price.

Want to learn more? Read Moissanite vs Diamond or explore our rings.

Frequently Asked Questions

Does moissanite pass a diamond tester?

It passes most standard thermal diamond testers. Electrical conductivity testers and gem labs can identify it as moissanite.

Why does moissanite test as diamond?

Because moissanite conducts heat almost as well as diamond, and basic testers only measure heat conductivity.

Can a jeweler tell moissanite from diamond?

Yes, with a multi-tester that checks electrical conductivity, or by spotting moissanite's double refraction under magnification.