Why is Moissanite sold by millimeter (MM) and not by carat weight?
In order to fit available settings, it is easier for jewelry manufacturers to order Moissanite by millimeter. The specific gravity of Moissanite is 3.21 grams per cubic centimeter, so a 6.5mm Round Brilliant Moissanite jewel is approximately 0.87 carats. Thus, Moissanite weighs less diamonds but are the same in diameter for their respective sizes. So, if you take a jewel to a jeweler and they weigh the stone do not be confused as to the weight, the jewel should be measured with a millimeter gauge for correct sizing.
*Sadly, we had to bring back ads too. Hopefully more targeted.