Kingman turquoise is the trade name for turquoise produced from the Mineral Park porphyry copper deposit near Kingman, in Mohave County, Arizona. The deposit has been worked, in one form or another, since pre-contact times, but the modern Kingman trade dates from the late nineteenth century and was consolidated under the Colbaugh family in the mid-twentieth, who continue to operate the turquoise lease as a by-product of the larger copper mine. Kingman is generally regarded, alongside Sleeping Beauty, Number Eight and Lone Mountain, as one of the four reference American sources whose names anchor the dealer trade in domestic United States turquoise.

Appearance

Kingman material spans a wide colour and matrix range. The classic appearance is a strong, even sky-blue body, often described in dealer language as Persian-blue, set within a black to dark-brown limonitic webbing inherited from the iron-rich host rock. Lighter, paler-blue material with a softer chalk-white matrix occurs in commercial volumes and is the basis of a great deal of the medium-grade Kingman seen in the American Indian jewellery trade. Less commonly the deposit yields green and bluish-green turquoise, sometimes traded as Kingman green, and a small fraction of pure-blue, web-free, gem-quality nodules that are cabbed without backing. Spider-web Kingman, in which fine, even black veining traces a regular network across a saturated blue field, is the most highly prized presentation and is sold under the dealer term water-web.

Treatment and stabilisation

Most commercial Kingman is stabilised, that is, impregnated with a clear epoxy resin to harden the porous structure and lock the colour. The Colbaugh operation has been transparent about this practice and grades its output as natural, stabilised, or composite. Natural Kingman, sold without resin treatment, is restricted to the harder vein material and commands a substantial premium, particularly in larger cut sizes. Reconstituted or block turquoise carrying the Kingman name in low-end markets is, properly speaking, ground turquoise rebonded with polymer and should not be confused with the natural or stabilised grades. Disclosure standards from the AGTA and the CIBJO Coloured Stone Book require treatment to be declared at the point of sale.

Position in the trade

Kingman is the most consistent large-volume supplier of American turquoise still in regular operation. Its longevity and its multi-grade output have made it the default reference for what Arizona turquoise should look like in the contemporary American Indian and Western jewellery trades. For Toronto buyers, the working assumption with any Kingman-marked material is that it is stabilised unless specifically certified otherwise; natural untreated Kingman, when available, is normally accompanied by a Colbaugh provenance card and is priced accordingly.