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 as well. 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.

There are almost 130 species of minerals that have been cut into gems with 50 species in common use. The names can be mentioned as Agate, Alexandrite and other varieties of chrysoberyl, Amethyst, this was originally a `cardinal gem`, but now no longer so, since huge quantities were discovered in Brazil and the price plummeted. The other names are Aquamarine and other varieties of beryl, Chrysocolla, Chrysoprase, Diamond, Emerald, Feldspar or moonstone, Garnet, Hematite, Jade i.e. jadeite and nephrite, Jasper, Kunzite, Lapis lazuli, Malachite, Obsidian, Olivine or Peridot, Opal or 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, and Zircon

Some of the minerals that infrequently occur in gem quality form can be mentioned as Andalusite, Axinite, Benitoite, Cassiterite, Clinohumite, Iolite, Kornerupine, Zeolite or Thomsonite. The other artificial or synthetic materials used as gems are as follows. High lead glass, synthetic cubic zirconia, synthetic corundum, synthetic spinel, and synthetic moissanite, etc.

There are also a number of organic materials used as gems. The names can be mentioned as amber, bone, coral, ivory, jet or lignite, mother of pearl, ammolite i.e. from fossils formed from the shells of extinct ammonites, pearl, and tortoiseshell.

Also read on Gemstones

Classification of Gemstones	Gemstones for Planets	Powers of Gemstones
Color Absorption & Reflection in Gemstones	Methods of Wearing Gemstones	Selection of Gemstones
Colors of Gemstones	Navratna Gemstone	Semi Precious Gemstones
Significance Of Gemstones	Synthetic Gemstones	Types of Gemstones

Types of Gemstones

Agate	Chrysoprase	Kunzite	Pearl	Tiger Eye
Alexandrite	Citrine	Lapis Lazuli	Peridot	Topaz
Amber	Coral	Malachite	Quartz	Tourmaline
Amethyst	Diamond	Moissanite	Rose Quartz	Turquoise
Aquamarine	Emerald	Moonstone	Ruby	Zircon
Aventurine	Garnet	Obsidian	Sapphire
Bloodstone	Jade	Onyx	Spinel
Carnelian	Jasper	Opal	Tanzanite

Gemstones for Planets

Blue Sapphire, Gemstone for Saturn	Emerald, the Gemstone for Mercury	Pearl, the Gemstone for Moon
Cat`s eye, Gemstone of Ketu	Gomed, Gem stone of Rahu	Yellow Sapphire, the Gemstone of Jupiter
Coral, the Gemstone for Mars	Ruby, the Gemstone for Sun	Diamond, Gem Stones for Venus