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A selection of gemstone beads made by tumbling rough rock
with abrasive grit, in a rotating drum. The biggest bead here is
40 mm long (1.6 inches).
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A gemstone bead is a mineral, rock, such in the case of lapis lazuli, or petrified material that when cut or faceted and polished is collectible or can be used in beading. Others are organic, such as amber, which is fossilised tree resin and jet, a form of coal. Some gemstone beads which may be generally considered precious or beautiful are too soft or too fragile to be used in beading, for example, single-crystal rhodochrosite, but are exhibited in museums and are sought by collectors. Read More.
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 Some beads 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 gemstone beads 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.
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A gemstone bead is prized especially for great beauty or perfection so appearance is almost the most important attribute of gemstone bead. Characteristics that make a bead beautiful or desirable are colour, unusual optical phenomena within the bead, an interesting inclusion such as a fossil, rarity, and sometimes the form of the natural crystal. Diamond is prized highly as a gemstone since it is the hardest substance known and is able to reflect light with fire and sparkle when faceted. However, diamonds are far from rare with millions of carats mined each year. Traditionally, common gemstones were classified into precious stones (cardinal gems) and semi-precious stones. The former category was largely determined by a history of ecclesiastical, devotional or ceremonial use and rarity. Only five types of gemstones were considered precious: diamond, ruby, sapphire, emerald, and amethyst. In current usage by gemologists, all gems are considered precious, although four of the five original "cardinal gems" are usually—but not always—the most valuable. Rare or unusual gemstones, generally meant to include those gemstones which occur so infrequently in gem quality that they are scarcely known except to connoisseurs, include andalusite, axinite, cassiterite, clinohumite and iolite.
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