A belt buckle by Lee Yazzie, in Lone Mountain Spider Web turquoise, uses the classic quadrant design of the Navajo. Credit Nancy Borowick for The New York Times

A belt buckle by Lee Yazzie, in Lone Mountain Spider Web turquoise, uses the classic quadrant design of the Navajo. Credit Nancy Borowick for The New York Times

Turquoise: A Complicated Stone

New York Times, May 13, 2015

In its most iconic form, turquoise looks like a clear blue sky. Beneath that tranquil surface, however, there is a complicated stone.

‘‘It is not about color,’’ said Joe Dan Lowry, co-author of ‘‘Turquoise: The World Story of a Fascinating Gemstone.’’ ‘‘It’s about the mine.’’

In antiquity, the finest turquoise came from the copper-rich mountains of Persia’s Khorasan Province. (Its name came from the Turkish traders who introduced the gem to Europe.)

In the 1970s, fashion embraced the blue and green stones mined in the American Southwest. Their veins or patterns in contrasting stone, called matrix, had been popular only with Native American silversmiths. ‘‘Matrix makes the patterns and character of the stone and magnifies its collectability,’’ said Joe Tanner, owner of Tanner’s Indian Arts in Gallup, N.M.

Now, the ’70s revival has brought turquoise back in a big way, but prices ‘‘are a nightmare to define,’’ Mr. Lowry said. And, ‘‘less than 3 percent of all the turquoise available today is natural and gem quality.’’

Which may explain something about turquoise lovers: ‘‘They’re hoarders at heart,’’ said Matthew Foutz, co-founder of Sterling Turquoise in Phoenix. ‘‘They’ll only part with their stones out of necessity.’’

Among the many varieties of turquoise, there are five notable kinds.

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Persian

From the mountains of Khorasan Province, Iran

Aristotle, Pliny the Elder and Marco Polo all mentioned Persian turquoise in their writings. It has a clear sky-blue color and now is available on the secondary market from dealers with old stocks.

A wholesale value of as much as $75 per carat.

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Bisbee

From Cochise County, Ariz.

Bisbee turquoise, with a deep blue color and smoky black matrix, is the byproduct of the ‘‘Lavender Pit’’ copper mine first prospected in the 1870s. ‘‘It has a blue of such intensity that it’s beyond anything the world has ever produced,’’ said Mr. Tanner, a fourth-generation turquoise trader.

A wholesale value of as much as $75 per carat.

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Kingman

From Mohave County, Ariz.

Turquoise production at Kingman began as early as A.D. 1000. It now is the top-producing mine in the United States. It is light blue to dark blue in color, with a white matrix usually dyed black; also comes in green.

Wholesale values range from $15 to $30.

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Chinese

From near Ma’anshan in Anhui Province, Hubei Province and other locations.

The Chinese began mining turquoise as early as 1700 B.C. China is now the world’s leading producer of turquoise. The color ranges from sky blue to spring green, and may or may not have matrix.

Wholesale values average $10 to $20 per carat.

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Sleeping Beauty

From Gila County, Ariz.

In the 1970s and ’80s, cameo makers in Torre del Greco, Italy, fell in love with Sleeping Beauty turquoise, and helped establish its global popularity. ‘‘Sleeping Beauty is the quarterback of all American gemstones,’’ said Mr. Foutz of Sterling Turquoise, a fifth-generation dealer. ‘‘No American gem is better branded or better recognized.’’ (The mine closed in 2012.) The consistent robin’s egg blue is easily matched.

A wholesale value of $50 per carat.