Will Moissanite Pass a Diamond Tester?
Yes, practically every time, moissanite will pass a regular diamond test. Standard tests check how well something conducts heat, and moissanite (silicon carbide) conducts heat so similarly to diamond that the tester can't tell them apart. Cubic zirconia, white sapphire, glass, and all other common diamond simulants fail this test right away. The sole exception is moissanite.Â
How Does Moissanite Pass a Diamond Tester?
Standard diamond testers work by putting a heated tip against the stone and seeing how quickly heat travels through it. Diamond is one of the best thermal conductors in nature, with a value of about 600 W/mK. Moissanite comes very close behind, with a value of about 490 W/mK, which is close enough for the tester's needle to swing into the "diamond" zone. The equipment isn't sensitive enough to pick up on the little difference between the two stones.Â
Why Does Moissanite Pass a Diamond Tester?
The main reason is because moissanite and diamond have very similar crystal structures. Both are covalently linked, very hard, and see-through. Moissanite is the closest gemstone to diamond (10) on the Mohs scale, with a score of 9.25. A harsh thermal test can't tell the two materials apart since they are so similar at the molecular level. It's not a problem with the tester; it's just how amazing moissanite is as a material.Â
Does All Moissanite Pass a Diamond Tester?
Most moissanite, whether it's made in a lab, found in nature, or bought from a well-known brand, will pass a conventional heat test. No matter how it was sliced, how much it weighs, or how it was made, silicon carbide has the same thermal conductivity. There is only one exception: very little stones that weigh less than 0.5 carats. In this scenario, a small contact surface might cause any tester to give inconsistent readings. If you don't know for sure, you should assume that moissanite will look like a diamond on a regular device.Â
How to Test Moissanite
A 10x loupe is the best tool for finding moissanite at home. If you look straight down at a facet edge, you'll see that diamond has a single clear line, but moissanite has a twofold line because its crystal structure is birefringent. Once you know what to look for, this always works. A UV light can also help, but this method isn't as reliable because moissanite often fluoresces in a different way than diamond. A GIA or IGI lab report will always tell you what kind of stone it is for sure. .
How to Test Diamond vs. Moissanite
A multi-tester that checks both thermal and electrical conductivity is the best way to tell the difference between diamond and moissanite. Moissanite conducts electricity, although diamond does not. After the thermal test, a two-step tester conducts a small electrical current. Diamond won't pass it, but moissanite will. When you look at moissanite next to diamond, you can see that its fire is much more colorful since it spreads light better (0.104 vs. diamond's 0.044). Moissanite makes rainbow flashes in intense light that diamonds just don't make with the same intensity.Â
Most Popular Moissanite Rings
The most popular moissanite rings look a lot like the diamond engagement rings that people like the most. Round brilliant solitaires are the best since the cut brings out the stone's fire and brilliance the most. Oval halo settings are a close second because they make the center stone look bigger and more spectacular. People adore cushion cut three-stone rings because they are classic and have a meaning. Pear-shaped stones on a pavé band look attractive and flatter the finger. People who like a modern, geometric style like princess cut solitaires. The elongated radiant cut has become very popular because of its bright, sparkling facets. Moissanite is usually 80–90% less than a similar diamond, thus all of these styles are affordable for almost any budget without losing any brilliance.Â
FAQ
Do lab grown diamonds test as moissanite?
 No. Lab grown diamonds are chemically identical to mined diamonds — pure carbon in a cubic crystal structure. They conduct heat exactly like a natural diamond and will read correctly as diamond on any tester, not as moissanite.
Do CVD diamonds test as moissanite?
No. CVD diamonds are real diamonds grown using a gas-phase process. Their thermal and electrical properties are identical to natural diamond, so any tester — thermal, multi, or lab report — will correctly identify them as diamond.
Do HPHT diamonds test as moissanite?
No. HPHT diamonds are real diamonds made by mimicking the high pressure and temperature conditions found deep in the Earth. They are chemically pure carbon and will always test as diamond. Some HPHT stones undergo colour treatment, but this has no effect on how they read on a diamond tester.
