"Viennese turquoise" is argillaceous earth that has been artificially blue-tinted. (Read this page to learn more about erroneous or misleading gemstone names.) Some natural gemstones can be confused for turquoise. Variscite can have the appearance of green turquoise. Prices for turquoise per ounce vary according to availability, carat, quality, grade, and rarity. One carat of turquoise equals.007 ounces and is priced according to grade and carat. Turquoise is used for a multitude of uses, the most common being jewelry making. There has been a significant number of turquoise jewelry manufactured in the previous 5,000 years, and there is still a lot being made now. Antique turquoise jewelry is collectible, and several aspects, such as quality, condition, kind of turquoise, creator, and age, will determine the piece's true turquoise worth. Quality unpolished turquoise or cabochons may be as precious as turquoise jewelry. "Viennese turquoise" is argillaceous earth that has been artificially blue-tinted. (Read this page to learn more about erroneous or misleading gemstone names.) Some natural gemstones can be confused for turquoise. Variscite can have the appearance of green turquoise.