Cast Crystal

How can you tell the difference between glass and a real crystal?

My kids bought a rose quartz crystal necklace and a large clear/white crystal from a specialty shop. Their friends are insisting the crystals aren't "real." I've heard some shops sell glass under the guise of being real crystals, but how do you tell?

Public Comments

1. One way to tell would be through how it is faceted. Minerals have defined crystalline structures that can only be cut into a gem/"crystal" form along certain fracture planes. Obviously, you can't really look at that, and neither can I. There are very few transparent minerals similar to glass enough to be mistaken (especially if you know how they fracture). Even fewer of these minerals are common enough to encounter in a normal crystal shop - as minerals that are being swapped for. To compare the possible glass against possible crystal, you'd need a sample of each, to see which one scratched (Mohs hardness) than the other. Basically, if you aren't familiar with identifying real minerals and their crystals, and all that you have is one crystal of something, there is very little that you can do. The only really possible way to try would be to take the Mohs scratch test to your crystals. Most of these possibly transparent crystals are softer than glass, and would scratch - but then you'd have a scratched crystal. I would recommend accepting the 99.9% chance that is is just glass, and enjoy it anyway.