Appraising Turquoise: Challenges for Gemologists

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.

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