Howlite and magnesite can easily be separated from turquoise using a refractometer. They have different refractive indexes. If you are willing to do a destructive test, the blue dye used to color howlite and magnesite generally does not penetrate very deep. If lightly dyed, scratching the back of a cabochon with a pin will often…

Howlite and magnesite are light gray to white minerals that often have markings that resemble the spider webbing seen in some turquoise. They can be dyed a turquoise blue color that makes them look very similar to natural turquoise. These dyed stones fooled many people when they first entered the marketplace and still are mistaken…

A small amount of synthetic turquoise was produced by the Gilson Company in the 1980s, and some of their material was used to make jewelry. It was produced in a sky blue color, sometimes with a gray spider webbing. It was a ceramic product with a composition similar to natural turquoise. Synthetic turquoise and turquoise…

Only a small amount of turquoise that is mined today can be used to cut finished stones or make jewelry without some type of treatment. These treatments make the turquoise stable enough for cutting, durable enough for jewelry, or improve its color and marketability. Untreated turquoise is a rare commodity. The rough, the stones cut…

The earliest record of turquoise being used in jewelry or in ornaments is from Egypt. There, turquoise has been found in royal burials over 6000 years old. About 4000 years ago, miners in Persia produced a blue variety of turquoise with a “sky blue” or “robin’s-egg blue” color. This material was very popular and traded…

Most of the turquoise production in the United States has been located in the arid southwest, and most of that production has been in or around deposits of copper. Arizona, New Mexico, and Nevada have all held the position of the leading turquoise-producing state. New Mexico held that position until the 1920s, Nevada held the position until the…

The turquoise group consists of five triclinic minerals. These minerals are very similar in chemical composition, crystal structure, physical properties and often in appearance. Members of the group are: turquoise, aheylite, chalcosiderite, faustite, and planerite. Their compositions are listed in the accompanying table. Notice that the members of the turquoise group have very similar chemical…

The physical properties of turquoise are valuable for its identification. They are also valuable information for the care of turquoise jewelry. Important properties are summarized in the accompanying table. Weathering can significantly alter the physical properties of turquoise. Weathered turquoise might still have a desirable color, but its hardness and durability are reduced. This turquoise…

Turquoise is rarely found in well-formed crystals. Instead it is usually an aggregate of microcrystals. When the microcrystals are packed closely together, the turquoise has a lower porosity, greater durability, and polishes to a higher luster. This luster falls short of being “vitreous” or “glassy.” Instead many people describe it as “waxy” or “subvitreous.” Turquoise forms…