MOISSANITE Some hard facts

It's made of silicon carbide, a mineral, in a laboratory.
It has more brilliance, more fire, more luster than a diamond.
It is lighter than a diamond.
It costs about a tenth as much as a diamond for the same carat size.
It won't scratch.
It is nearly as hard as a diamond. Diamonds register 10 on a standard scale used by jewelers. Moissanite registers 9.25, ahead of rubies and sapphires at 9 and emeralds at 7.5.
Compare for yourself
Rhinestone: An artificial stone made of hard glass and cut to look like a gem. One carat, starting at $3.
Cubic zirconia: The cubic form of zirconium oxide; grown in the lab. One carat, about $100.
Moissanite: Lab-created gemstone made of silicon and carbon. One carat, about $450.
Diamond: A mineral made of carbon. One carat, about $4,500.