Gem: a material of natural origin, either inorganic or organic, that is transparent, semitransparent, translucent, or opaque, and is cut and polished to reveal its intrinsic beauty—resulting from the play and brilliance of light and color produced by its polished surfaces—along with qualities of rarity and durability. Gems are used for personal adornment. Most gems are of inorganic origin, meaning they are minerals (with the exception of lapis lazuli, which is the only gem classified as a rock), formed through chemical and physical processes within the lithosphere. Organic gems, derived from plant or animal activity, include: Amber, Ammolite, Ivory, Coral, Jet, Fossilized Wood, Pearls, and Tortoiseshell.
