Moissanite Sizing to Carats Cheat Sheet

How are moissanites sized?

Unlike diamonds, moissanite are sized in millimeters. Why is that? Moissanites are measured as such because they weigh less than an actual diamond. There is about a 15%-18% weight difference between both of the stones.

So how will this affect my purchase?

Moissanites are priced based on their measurements. No matter the weight of the stone, they are sold strictly on the measurements. The moissanite stones may measure different in weight but will measure close or the same in diameter.

Do carats still apply to moissanites?

We’re not trying to trick you but this is a yes and no answer. Let us explain!

All stones have a carat weight, but are sold in different ways. Moissanites are sold by their calibrated size, not by their weight. On the other hand, diamonds are sold by their carat weight. Seems simple enough, right?! We refer to the sizing in "carats" to give you the most familiar sizing comparison. To be clear, the is truly no carat sizing with moissanite but all of our stones are within .25 "carats" of what would typically be the size of that carat weight.

For a better understanding, there are conversion charts to show how both the weights and sizes compare between the two.

How do mm and carat sizing compare?

Different gemstones will have different weight translations and different styles of cuts with the same diameter measurements will weigh different. A good example is a 7.5mm cushion moissanite; it is the rough weight equivalent of a 2-carat cushion cut diamond. On the other hand, a 7.5mm round moissanite is equivalent to 1.50 carat round cut diamond.