What are Gemstones?

From ancient times many materials, natural and artificial, have been set in jewelry and other precious objects. Over the centuries however, the term gemstone has come to mean a naturally occurring mineral desirable for its beauty, valuable in its rarity and sufficiently durable to give lasting pleasure. Most gemstones are minerals that have formed in a variety of environments within the earth. Minerals have a definite chemical composition and ordered atomic arrangement so that their physical and optical properties are constant or vary only within narrow limits. These properties, such as density and refraction, can be measured accurately and are used to identify a mineral.

Ideally gemstones should be hard and unaffected by the temperatures, pressures, abrasive dusts, and chemicals encountered in our everyday lives. The majority are Beryls, and include Emerald, Aquamarine, Peridot, and Amethyst, as well as many exotic rarities. Ruby, Sapphire, Spinel, and Chrysoberyl are oxides. Diamond is unique among gems in being composed of a single chemical element carbon. Nephrite, Jadeite and Lapis Lazuli are rocks, that is, aggregates of one or more minerals.