Many qualities and types of turquoise are available on the market today. The following are terms often used by dealers to describe the grade of turquoise that is available for sale. You should bear in mind, however, that sellers often misclassify turquoise, either accidentally or deliberately.

High-grade Natural Turquoise

This is the hardest grade available, and there is very little left in North America. Many mines produce stones with distinctive color or matrix whose origin can be identified by an experienced person.

Fig. 1: Raw Natural Turquoise from Kingman Mine (Colbaugh's)

Enhanced Turquoise

"Enhanced turquoise" refers to medium-grade turquoise that has been treated by a process that penetrates and hardens the stone with vaporized quartz. The process will only work on fairly hard turquoise. It will not work on low-grade "chalk" turquoise. Enhancement of turquoise is usually undetectable by normal testing methods.

Color Enhanced Turquoise

The term "color enhanced" means that the turquoise has been treated with dye.

Fig. 2: Stabilized and Color Enhanced Turquoise

Stabilized Turquoise

Turquoise referred to as "stabilized" has been treated with a plastic resin to harden it. This is often done at the original mine. Most nugget and heishi products now available in North America are made from real turquoise that has been stabilized. Stabilization allows genuine but lower-grade turquoise to be used in jewelry. Even when a stone has been stabilized, its color can be changed over time by pollution, soap, skin lotion and oil.

Fig. 3: Color Range - Stabilized Turquoise Beads - Kingman (Colbaugh)

Fig. 4: Green Turquoise from Kingman or Southern Nevada

Wax-treated Turquoise

Wax is sometimes used instead of plastic resin to stabilize turquoise. Much of the turquoise from China is wax impregnated. The paraffin treatment only affects the surface.

Reconstituted Turquoise

"Reconstituted" or turquoise consists of small pieces of stone and turquoise chalk powder mixed with dye and plastic binder. This type of turquoise is sometimes often referred to as "block." Fake turquoise is also often labeled "reconstituted." Sometimes it's almost impossible to tell, as in the picture below.

Fig. 5: Imported Turquoise Beads Sold as "Reconstituted"

Block Turquoise

"Block turquoise" is a mixture of plastic resin, chemicals and dyes that produced in loaf-size blocks. Block turquoise contains no actual turquoise of any sort. Iron pyrite is sometimes used for a "matrix" effect. Block is often used for inlay, heishi and beads. It is sometimes mistakenly called "reconstituted." This imitation turquoise is often marketed as "chalk" or "stabilized" turquoise, especially by Asian distributers.

Fig. 6: Block (Fake) Turquoise in Jacla Type Necklace

Fig. 7: Block (left) and Stabilized (right) Turquoise Side by Side

Other Imitation and Simulated Turquoise

Some stones maybe be dyed to look like turquoise, including howlite, magnesite and dolomite. Glass, plastic, ceramic and polymer clay may also be made to look like turquoise. There are dozens of recipes for polymar (Fimo) turquoise on the Internet. Imitation turquoise is sold under many, many names.

Figure 8. Fake Turquoise ("Mountain Turquoise") Squash Blossom

"Sacred Buffalo" versus "White Buffalo" turquoise

Sacred Buffalo turquoise is a pale, usually blue, turquoise mined at Dry Creek Mine in Nevada. Recently, natural white howlite - a stone much cheaper than turquoise - has been marketed at a premium price as "White Buffalo" turquoise. It is not turquoise.

Figure 9. White Howlite Bracelet ("White Buffalo Turquoise")

Apple Green, Yellow, Purple Turquoise

These and other exotically colored turquoise types are usually either block (fake) or dyed howlite.

Figure 10. Dyed Howlite Bracelet ("Apple Green Turquoise")