Not gems at all, but organic stones produced by mollusks, Pearls are composed of calcium carbonate built up in concentric layers into a perfectly round, smooth shape. Nowadays, most Pearls are cultured from pearl oysters and mussels, but the rare naturally occurring “Wild Pearl” can still be found here and there. Pearls have long been revered as exotic objects of beauty, and for this reason, artificial Pearls are very common in the fashion world, often found stitched into clothing or even crushed for use in cosmetics and paints. But it’s quite easy to distinguish synthetic Pearls from the bona fide stone. Gem-quality Pearls possess an iridescence and luster, the degree of which depends upon the reflection, refraction and diffraction of light on the stacked layers of the stone. Real pearls will eventually dissolve if immersed in vinegar. This is June’s birthstone.