Traditionally, one of the most well-known tests for a diamond was to see if it cut glass. The idea was that only a diamond would be truly hard enough to actually cut glass.
Unfortunately, in today’s more scientific world, that folksy tale has been debunked. It has to do with something called the Mohs scale. The Mohs scale is a test for an object’s mineral hardness. So, for instance, if glass is a 5.5 on the Mohs scale, then surely a diamond, which is a 10, can cut it. And it does, but the thing is…so do a lot of other stones—quartz, for example, which is a 7, or even cubic zirconia, which is an 8.
Moissanite stones are not exactly as hard as a diamond, coming in a 9.25, but that’s still plenty hard enough to cut glass and pass the last century’s diamond test. In fact, that score makes moissanite the second hardest gemstone, just shy of diamond. It’s why sustainable, lab-created moissanite has been so popular as an alternative for diamonds in industrial uses for so long. But now the tech exists to make moissanite not only as hard and durable as diamond but with greater clarity and fire as well. And since the stones are inherently created to be flawless, you can get a pretty close to perfect moissanite gemstone for a lot less than what you would pay for the equivalent diamond.