Treating turquoise
The Zachary Enhancement Method was developed by James E. Zachary, an electrical engineer and trader of turquoise. Moderate- to high-grade turquoise is subjected to a proprietary chemical bath and then heat-treated. This creates a harder material that
takes a superior polish to natural untreated turquoise. This process doesn’t make the material any stronger, but the effect is achieved without the use of dyes or additional hardening agents. The specific gravity of Zachary-treated turquoise is reputed to be lighter than its natural counterpart.
Stabilized turquoise results from soaking rough low-quality turquoise in a bath of resin, epoxy, or some sort of liquid plastic; newer stabilization methods include using pressure to help impregnate the plastic farther into the turquoise rough. Sometimes, dye is also introduced into the bath to provide a deeper and more even colour distribution. The resultant material after cutting and polishing may exhibit a harder surface with greater lustre. The stabilized turquoise is also protected from dirt and doesn’t display a ‘bloom’ that may occur with turquoise treated with less stable materials (i.e. wax or oil) and which may leak out, changing the colour of the material. Stabilized turquoise may be identified by its lower specific gravity. Superior hardness and a very high lustre are indications the material has been stabilized.
Reconstituted turquoise consists of pieces of natural turquoise that are too small to be useful. These very small pieces are ground into a powder and mixed with a binding agent. The mixture is then moulded into slabs and allowed to dry. After it has dried, it may be sliced, carved, or cut into cabochons. Reconstituted turquoise is very inexpensive to produce and is often found in low-priced fashion jewellery. The specific gravity is lower than that of natural turquoise and is often key in its identification.
