Gem or gemstone that is highly appealing and very costly, exhibiting a powerful luster, high hardness, and rarity.
Term limited to diamonds, emeralds, rubies and sapphires; pearls are also usually included. Other gems tones are generally termed semiprecious. The value of precious stones depends on rarity, size and quality, and on workmanship, such as faceting.
a gem distinguished for its beauty and rarity, used in jewelry.