A Cubic Zirconia can be spotted using ultraviolet light as well. Where
diamonds will glow blue under UV light, Cubic Zirconia will glow mustard
yellow.
If you suspect that the jewelry you have purchased is Moissanite, make sure
to see a jeweler who is well versed about Moissanite and has the equipment
to test your gem.
Another way to spot a fake is by the setting and mount that it is placed in.
Fake diamonds are often set in low quality inferior metals with cheap mounts.
The best way to be sure that you are purchasing (or have received) a real
diamond is to bring it to a certified gemologist who can give it a
LINK REMOVED certification.