A term that in past years has been applied to a gemstone of a small group limited to the diamond, emerald, ruby, and sapphire, with which the pearl, although not a stone, is usually included. Thebasic monetary value of such stones depends upon rarity, size, and intrinsic quality, although it is also affected by the quality of the workmanship, such as faceting, but apart from considerations ofsetting.The term 'precious' is sometimes used to indicate a variety of a stone, e.g. precious opal. It is also sometimes loosely prefixed to the name of a gemstone to distinguish it from another variety ofstone that resembles it, e.g. 'precious topaz' which is citrine; such usage involves a misnomer and should be discontinued.