Classification of treasure Diamonds, rubies, sapphire, emeralds, aquamarine, cat's eye gemstones, discolored gemstones, citrine gemstones, opal, tourmaline, splendid gemstones, garnet gemstones, zircon gemstones, olive emeralds, emerald emeralds, quartz cat's eye, Feldstone gems and so on. The classification of jewellery knowledge lists the approximate types of gems.