Can Moissanite Pass a Diamond Tester? What You Actually Need to Know

Short answer: yes, some moissanite passes basic diamond testers. That's why this matters. Understanding the science behind the tester saves confusion when you're buying or verifying a stone.

How diamond testers actually work

Most handheld diamond testers measure thermal conductivity, how quickly a stone moves heat through itself. Diamond conducts heat very efficiently, with a specific signature the tester is calibrated to recognise.

Moissanite's thermal conductivity is lower than diamond's, but higher than most other gemstones. That's a grey area for older testers, especially budget ones. Some can't tell the difference between moissanite and diamond reliably.

Testers built since around 2015 are more sensitive and pick up the difference. But not every jeweller has updated their equipment.

The electrical test that actually works

The real answer is electrical conductivity. Moissanite conducts electricity. Diamond doesn't. That's a binary, not a grey area.

A combined tester (Presidium PWGL Pro and similar) checks both thermal and electrical signatures. It identifies moissanite with 100 percent accuracy.

At our studio we use this kind of tester. If you're buying moissanite from us, or want to verify a stone you've bought somewhere else, we can run the test in five minutes.

Why this matters in practice

If you inherit a ring, or buy secondhand, you want to know what you actually have. A proper test removes the guesswork. We do this for customers regularly, including stones bought elsewhere. There's no fee for the check.

The deeper point: any jeweller who tells you their moissanite will "pass any diamond tester" is either misrepresenting the stone or using outdated equipment. Reputable moissanite suppliers are upfront about how electrical testers identify the stone. We are. That transparency is the only sensible position.

What confident moissanite buying looks like

You should receive:

• A stone with lab documentation (Charles & Colvard certification or equivalent)
• The option to test it yourself with an electrical conductivity tester
• A jeweller who explains testing openly without dodging the question

That's the standard at our studio. Every stone comes with documentation, we use the right testers, and we explain exactly what a test result means.

If you want to compare stones in person or have one tested, come into the Southbank studio. We'll show you what's what.