Imitations of turquoise are common, and many of these origi­nate in the East, although the real stone is also often carved by the Chinese into small figures and ornaments. Colored glass and china of a pale blue color to imitate the real stone are often seen, but a superficial glance is generally sufficient to distinguish them. A more ingenious material which may deceive is the one made from clay into which markings have been introduced, and this looks much like turquoise matrix. A glassy or highly polished surface should always promote suspicion, since the natural stone will not take a good polish. Again, many so-called turquoises are really odontolite or variscite, two natural minerals which greatly resemble turquoise in appearance although not in other respects. Variscite is more extensively used in the cheaper forms of jewelry than is generally realized; its popularity is due to its cheapness and to its similarity to turquoise when it is suitably set and treated for color.

Variscite is a hydrated phosphate of aluminum, and in its natural state resembles greenish turquoise in color, but it is softer, (having a hardness of only 4) and also lighter, the specific gravity being 2.55 and sometimes lower. It is found in large masses in both Utah and Nevada. The Nevada mines are centered at Colum­bus, an all but deserted mining camp situated some 4,600 feet high in an almost desert region.

Surface digging is sufficient to uncover the material, and no deep mining is necessary. It is found as nodules or as a filling in the fissures and joints of the crystallized limestone and shale formations. Pale to fairly dark green stones are cut, some weighing upwards of 25 carats, but they realize very little. Other stones are cut with the matrix to show varied effects, just like turquoise, and they are often sold to tourists in Nevada.

Odontolite, or bone turquoise, is simply fossil bone, stained blue or green by iron phosphate. It has a higher specific gravity than turquoise, 3 to 3 1/2, but a lower hardness of 5. The bony structure may be easily recognized, and contact with hydrochloric acid will produce an effervescence on account of the presence of calcium carbonate. Natural turquoise would dissolve without effervescence.

As a gem stone, lack of hardness and instability of color are the chief disadvantages of turquoise. In addition, its color restricts its suitability in wear for many people, but its use in jewelry is most attractive when worn with discrimination. It harmonizes well with gold or silver, and its fine, pale blue color is unlike that of any other stone. Good specimens are sold by the carat, but even so, they usually sell for less than a few dollars per carat.

Turquoise is sometimes spelled turquois, turkoise, and turkis. The term is of Tartar origin, for the stone originally came to Europe from Turkestan, possibly through Turkish hands.