Moissanite Testing

is it a diamond or moissanite?

© by Dennis Shea; all rights reserved

Moissanite is the only stone to fool diamond testers because of its similar physical properties. Here are some facts on how it compares to diamond:


Moissanite vs. Diamond
moissanite diamond
refractive index (RI) 2.65 - 2.69 2.42
hardness 9.25 10.0
dispersion 0.104 0.044
luster 20.4% 17.2%
toughness good good

Moissanite has a hardness of 9.25, which is second to diamond. It will always weigh a little less than a diamond of the same size, but will have more brilliance (sparkle). Most moissanite ranges from nearly colorless to shades of light green; medium and dark green are also available.

How can you find out if your stone might be moissanite? There are only three methods of distinguishing it from diamond:

  1. check with a moissanite tester

  2. determine if doubling of facet junctions is visible through magnification

  3. look for needle-like or micro-pipe type inclusions that are only visible through magnification.

There are lots of moissanite testers on the market that do a great job of letting you know whether the stone is a diamond. One tip for using a tester is to check multiple places on the same stone.

Although trained diamond graders will most likely see that something doesn't look right when looking into a moissanite stone, it has been known to get by some professionals.


Author Dennis Shea of National Jeweler's Supplies offers over 1,000 quality products to the professional jeweler, craftsman, and hobbyist. Save on everything from anvils to tweezers, diamond and gold testers, loupes, microscopes, equipment, and tools.


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