Today there not only fake or treated gems in the market, technological advances have brought in imitation gems, “lab-grown” simulations gems and synthetically produced gems. There are widely believed misconceptions about these new kinds of gems and it's important we clarify them here, before purchase. Imitations gems [such as glass or plastic gems] are made to look like real gems, but their chemical compositions are nothing like real gems, and they will be easily unmasked as imitations in any standardized testing [or even with a loupe if you spend a minute examining several gems of the same type and recognize the difference]. These are mostly worthless, as they only simulate color -but nothing else, and should sell for very low prices that are utterly out of range of any real gem.