Turquoise AppraisingTurquoise Appraising

Turquoise Specialist Mini Course

Turquoise Appraising

appraising turquoise - silver and gold turquoise ring
Yellow gold and sterling silver ring with a turquoise oval cabochon center stone and Swiss blue topaz accents. Photo by CustomMade. Used with permission.

Determining if Turquoise is Natural, Treated, or Synthetic

Unless you can definitively rule out treatment, assume any turquoise has received some form of treatment.

How Common is Treated Turquoise?

Less than 5% of mined turquoise qualifies as gem-quality without any modifications. That leaves 95% of the natural yield unsuitable for jewelry. Miners would rather not throw away all that material. Thus, approximately 98% of all turquoise on the market has received some treatment. These include impregnation or stabilization, dyeing, and the proprietary Zachery treatment. All these techniques can improve the appearance and durability of otherwise unusable turquoise. Unfortunately, identifying these treatments with standard gemological equipment is often very difficult.

carved doublet - Kingman, Arizona
Carved doublet cut from stabilized turquoise from Kingman, Arizona. This famous source now produces little quality material, but this piece was cut from old rough. © 49erMinerals. Used with permission.

Can You Detect Turquoise Treatments?

You might get lucky with a loose turquoise and detect a specific gravity lower than usual. This may indicate impregnation. You might also see damage

Emily Frontiere

Emily Frontiere is a GIA Graduate Gemologist. She is particularly experienced working with estate/antique jewelry.

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