Room 101 Jewelry

A Note on the Different Types of Turquoise Used in Jewelry Today

You may be contemplating buying a piece of turquoise jewelry. That would not be unusual because turquoise jewelry is in great demand today, and turquoise itself is the most popular gem that is opaque. When you set out find out more that special silver turquoise pendants, you will probably encounter a range of different expressions related to turquoise. To a novice, that might be a bit confusing and more than a little intimidating. This article has been written to describe the various types of turquoise in the market today. In order to better understand these terms, it is useful to first have some basic knowledge about this mineral. The development of turquoise started a few million years ago when copper and aluminum salts precipitated out from solution and slowly started to harden because of the application of the geologic action of extreme pressure and high heat. The best quality turquoise today comes from Iran. Mines in Arizona are also quite famous for the high quality specimens found here. Turquoise from South America and China are known to be of low to moderate quality.

• The highest quality of turquoise is called gem-quality turquoise. These specimens are of sufficient hardness and density so that they can be cut and polished and used in jewelry designs without additional treatment. Less than 5 percent of the world’s production is of this high quality, and it is quite expensive. Too expensive in fact to be used in fashion jewelry, and is typically reserved for fine jewelry.
• Treated turquoise is made by soaking a piece of turquoise in vegetable oil or paraffin wax. This does nothing to improve the physical properties and behavior of the stone, but does give it a temporary shine. In the strictest sense of the term, this does not qualify as a stabilizing treatment.
• Stabilized turquoise is created by soaking a moderate or even low quality specimen in liquid epoxy resin. The liquid penetrates the stone either solely under the forces of matric suction, of may be forced in by simultaneous application of pressure and vacuum. Once the stone has been sufficiently infused, it is allowed to dry, during which time the epoxy resin hardens. This treatment blocks the pores in the stone and improves its hardness. A low to moderate quality specimen which previously could not be cut and polished, can now be finished and used as that pendant in your white pearl necklace .
• Enhanced turquoise is the next step up in the process of stabilization. Here, vaporized silica is used as a stabilizing agent. The principle is the same as with epoxy resin. The stone is infused with the stabilizing agent and then allowed to dry and harden. The different is that this is a much more rigorous than epoxy treatment, and even an experienced jeweler will find it hard to detect silica stabilization.
• Reconstituted turquoise is formed by crushing waste and low quality turquoise to a fine powder, mixing it with a clear resin, and then allowing it to dry in box molds. After the blocks harden, they are cut into the required shapes. This is the lowest form of turquoise, and it can be easily recognized because the characteristic dark veins are missing from the surface and the interior of the stone.

About the Author

Dale is a geo-professional in the Southwestern United States, and an avid and amateur gemmologist and a jewelry buff.

Molds for epoxy jewelry