Synthetic and artificial gemstones
Some gemstones are manufactured to imitate other gemstones. For example, cubic zirconia is a synthetic diamond simulant composed of zirconium oxide. The imitations copy the look and colour of the real stone but possess neither their chemical nor physical characteristics. However, true synthetic gemstones are not necessarily imitation. For example, diamonds, ruby, sapphires and emeralds have been manufactured in labs, which possess very nearly identical chemical and physical characteristics to the genuine article. Synthetic corundums, including ruby and sapphire, are very common and they cost only a fraction of the natural stones. Smaller synthetic diamonds have been manufactured in large quantities as industrial abrasives for many years. Only recently, larger synthetic diamonds of gemstone quality, especially of the coloured variety, have been manufactured.
Gemstone list
There are over 130 species of minerals that have been cut into gems with 50 species in common use. These include:

Agate
Alexandrite and other varieties of chrysoberyl
Amethyst (originally a "cardinal gem", but now no longer so, since huge quantities were discovered in Brazil and the price plummeted)
Aquamarine and other varieties of beryl
Chrysocolla
Chrysoprase
Diamond
Emerald
Feldspar (moonstone)
Garnet
Hematite
Jade - jadeite and nephrite
Jasper
Kunzite
Lapis lazuli
Malachite
Obsidian
Olivine (Peridot)
Opal (Girasol)
Pyrite
Quartz and its varieties, such as tiger's-eye, citrine, agate, and amethyst
Ruby
Sapphire
Spinel
Sugilite
Tanzanite and other varieties of zoisite
Topaz
Turquoise
Tourmaline
Zircon

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