An artificial stone that is man-made to imitate, often its colour, the appearance of a natural gemstone, but having wholly different physical characteristics (e.g. hardness, specific gravity, colourdispersion, double refraction, dichroism) as well as different chemical composition, and hence also distinct from a synthetic gemstone. Examples (called 'simulants') are usually made ofvarious types of glass (e.g. paste or strass) or plastic; such copies are moulded and hence are not required to be cut or faceted.