What is turquoise?

Turquoise is a beautiful blue-green gemstone found throughout the world. It has been actively mined and used for jewelry since at least 3,000 BCE. Because turquoise is comprised at least in part of copper, it is often found in the vicinity of copper mines and copper deposits. Some of the best quality turquoise has been mined in Iran since the very earliest of times. Here is a sample of uncut turquoise as found in Arizona.

In the United States, turquoise is most commonly found in the southwest, although deposits have been found in other states including Virginia. Most of the known turquoise deposits in the west have been depleted and only a few active mines remain.

American turquoise is generally considered to be of a lesser quality than much of the turquoise found in Iran and other parts of the world (and priced accordingly). In fact, most American turquoise is considered "low grade" and is commonly referred to as "chalk turquoise." Almost all of the turquoise jewelry sold in the American southwest, is made from chalk turquoise (or some form of imitation turquoise; see below). Even though most American deposits are poor grade turquoise, some high grade deposits are still being found in Nevada.

Turquoise is a relatively soft gemstone. On the Mohs scale, it rates only a 5-6, only slightly harder than ordinary window glass and substantially less than quartz (7) or diamonds (10). In part due to its softness, and in part due to its chemical composition, turquoise is very susceptible to damage. It is common for the turquoise miner/producer to stabilize the turquoise by high pressure injection of epoxy or polystyrene to improve its durability. Although not commonly done outside of the American southwest, most American turquoise is also "backed" meaning that an epoxy steel backing has been applied to the turquoise to help prevent it from cracking. Light oiling or waxing of the turquoise is also common to improve its luster, although purists may object to any kind of treatment. Neither stabilization or backing decrease the value of turquoise, but both do improve its durability and practicality in fine jewelry. Here is an example of stabilized, backed American turquoise set in sterling silver in a delicate, organically themed piece from my collection.

In contrast to the above, when I designed and made these post backed sterling silver earrings, I wanted a less elegant and less refined look to the pieces, so I used turquoise that had not been stabilized, oiled or waxed and you can actually see the natural fissures in the gemstones.

As with anything of value that is subject to scarcity, there are those who will try to make an inexpensive product look like something that is rare and expensive, and sell it to an unsuspecting buyer. That is also true of turquoise. Among the many turquoise imitations passed off as true turquoise, are dyed magnesite, howlite, chalcedony and even common marble. More recently, technology has allowed the creation of many kinds of imitation turquoise, including Viennese turquoise and Gilson turquoise. Without extensive experience, education and testing tools, most of us are not able to distinguish most of these imitation products from the genuine product and sometimes even the experts are fooled. To try to protect myself from inadvertently buying imitation products, I always try to buy from known, established sources. At least once each year, I travel to the mining districts in Nevada and purchase gemstones directly from the sources. (Sadly, bead shows and some "household name" auction and online sites, have the largest percentage of purveyors of undisclosed, imitation gemstones.)

Below is a sample of imitation turquoise (dyed howlite), before cutting and polishing. As you can see, it has the coloration and veining that you would expect from genuine turquoise. Only a professional could tell the difference.

As with most natural products including gemstones, care must be taken to protect and preserve the beauty of the gemstones. Perfume, cosmetics, skin oils, commercial cleaning fluids, sunscreen and hair spray will all damage turquoise. Additionally, prolonged exposure to the sun will dehydrate the turquoise and cause discoloration. "Sonic" cleaners should not be used to clean any gemstone that is subject to fracture.