Natural vs. Stabilized Turquoise: A Complete Guide to Treatments
Natural turquoise — hard enough to grind and polish without any treatment — represents roughly 15 percent of total world production. The other 85 percent is chalk: material too soft to cut for jewelry without intervention. Every treatment type from surface waxing to the Zachery electrochemical process to full reconstitution is documented here.
Mateo's Field Notes
The hardness problem drives the entire treatment industry. "An average of 85 percent of the total mining production of turquoise yields turquoise that is too soft…" (Lowry, Turquoise: The World Story, ~line 9800.) Chambless frames the same fact from the other end: "Turquoise is relatively soft, and it is estimated that at least 80 percent of it is too soft to cut successfully for jewelry without having the stone cracking, losing luster, or changing color." (~line 10500–10515.) Both sources agree: gem-grade natural turquoise is the exception, not the rule. As Chambless puts it, "Natural (untreated) high-grade turquoise is among the rarest of all gemstones, certainly far above diamonds, and gem-grade is the rarest of the rare." (~line 10500–10515.)
The stabilization industry has a specific origin story. Lowry documents it in some detail: "In the United States during the 1950s and 1960s, on the sunporch of an unknown old man's home, which was located on a hillside above Globe, Arizona, Leonard Hardy and several others were introduced to 'soak treating' turquoise." (~line 9820–9870.) The original electrochemical method was blunt: "place 'chalk' turquoise in a large stainless steel pan with electrodes placed at each end. Next, they added petrochemicals and blue dye along with the chalk and then generated volts of electricity to impregnate the turquoise and the chemicals together." (~line 9820–9870.) The result is firmer stone — but Lowry is unambiguous: "Stabilized turquoise is not natural turquoise."
The most sophisticated modern treatment is the Zachery process, developed by Jimmy Zachery. Lowry describes it: "Jimmy's science and turquoise background combined to develop beautiful-looking turquoise. This patented process can be used to treat either cut cabochons or rough turquoise." (~line 9920–9960.) Two variants exist: a "clear shot" with no added dye and a "color shot" with dye. A side effect of the process changes the stone's index of refraction, making the color appear darker.
Kitchen and surface treatments predate the industrial era. Applying Crisco, mineral oil, or wax to soft turquoise is the oldest stabilization method — documented by Lowry — and entirely temporary: the surface enhancement fades with wear and heat.
At the far end of the spectrum, the Gilson synthetic emerged in the 1970s. Lowry: "In the 1970s, he [Pierre Gilson] developed a synthetic turquoise that was said to be mineralogically identical in every way to natural turquoise. This process produced an imitation to the clarity and robin's-egg blue color of Persian turquoise." (~line 9990–10040.) A black matrix version was subsequently added. Gilson synthetic is not mined turquoise of any grade — it is a laboratory creation.
[HELD] — A passage in Bedinger (~line 858) references the introduction of altered and imitation turquoise in the railroad era. The OCR text is partially garbled at the name of the individual credited; this attribution is held pending corpus verification.
Collector's Handbook
- Treatment taxonomy. From least to most intervention: (1) natural/untreated, (2) surface-oiled/waxed, (3) fracture-sealed (resin in cracks only), (4) stabilized (full resin impregnation), (5) Zachery-treated (electrochemical, no resin), (6) blocked (compressed crumbs), (7) reconstituted (powder + binder), (8) Gilson synthetic (lab-grown).
- Ask the right question. "Is this natural?" is the start; "Which treatment process?" is the follow-up. Sellers who cannot answer the second question cannot verify the first.
- Zachery vs. stabilized. Both improve hardness; only Zachery avoids resin. Neither produces natural turquoise. Both require disclosure under FTC guidelines.
- Blocked vs. reconstituted. Blocked stone = compressed fragments (some mineral integrity preserved). Reconstituted = powdered to dust and re-formed (mineral structure destroyed). Both are far from natural.
- Gilson trap. Because Gilson synthetic may be mineralogically similar to natural stone, basic hardness tests can mislead. Seek gemological certification from a lab equipped to distinguish synthetic from natural.
- Price signal. Natural gem-grade turquoise at market rates is expensive. Deeply discounted "natural" turquoise is almost certainly treated or imitation.
Related Entries in the Directory
See the Silversmith Directory for artists who source and disclose material treatments. See also Turquoise Imitations and Fakes for materials that are not turquoise at all.
Primary Sources
- Lowry, Joe Dan & Joe P. Lowry. Turquoise: The World Story of a Fascinating Gemstone. Gibbs Smith, 2010, ~line 9763 (natural 15%); ~line 9800 (chalk 85%); ~line 9820–9870 (stabilization origin, Globe AZ; electrochemical method); ~line 9920–9960 (Zachery process); ~line 9990–10040 (Gilson synthetic).
- Chambless, Philip & Mike Ryan II. Turquoise in America, Part One: The Great American Turquoise Rush 1890–1910. Callais Press, 2021, ~line 10500–10515 (hardness/rarity statements).
- Bedinger, Margery. Indian Silver: Navajo and Pueblo Jewelers. University of New Mexico Press, 1973, ~line 858 ([HELD] — imitation turquoise introduction, OCR garbled).