ETYM Old Eng. gemme precious stone, French gemme, from Latin gemma a precious stone, bud.
1. A crystalline rock that can be cut and polished for jewelry; SYN. gemstone, stone.
2. Something highly prized for its beauty or perfection; SYN. treasure.
Mineral valuable by virtue of its durability (hardness), rarity, and beauty, cut and polished for ornamental use, or engraved. Of 120 minerals known to have been used as gemstones, only about 25 are in common use in jewelry today; of these, the diamond, emerald, ruby, and sapphire are classified as precious, and all the others semiprecious, for example the topaz, amethyst, opal, and aquamarine.
Among the synthetic precious stones to have been successfully produced are rubies, sapphires, emeralds, and diamonds (first produced by General Electric in the US 1955). Pearls are not technically gems.
With the exception of the diamond, most stones are valued for their color. However, this is often due to the presence of pigmentary matter, and not a property of the mineral itself. The most common mineral pigments are probably compounds of iron, manganese and copper. Exposure to light makes some stones change or lose their color altogether; certain types of turquoise and topaz are particularly liable to do this. + prikaži više