Turquoise, the traditional birthstone of December, is also gifted on the 11th wedding anniversary. But buying turquoise doesn’t require a special occasion. Its namesake blue color has been internationally revered for centuries as a symbol of protection, friendship, and happiness.
Thanks to its historical and cultural significance in many Native American tribes, turquoise remains most popular throughout the southwestern U.S. This area supplies most of the world’s turquoise today.
Turquoise is one of few gemstones not judged by the 4Cs of diamond quality. Instead, the main factors that determine its value are color, matrix, hardness, and size.
The most prized turquoise gemstone color is a bright, even, sky blue. Greenish tones can lower the value of a stone, although some designers prefer it.
Some turquoise—particularly the material mined in the American Southwest—contains remnants of its host rock, known as matrix. These splotches decrease a gemstone’s value. Although it can create an attractive “spider web” pattern, unblemished varieties command higher prices as jewelry.
The porosity, texture, and hardness of turquoise vary greatly. Fine-colored turquoise that’s too soft or chalky will lose color—and value. Course, porous material is usually treated to make it stronger, smoother, and shinier.
Because of its fragility, turquoise is often treated to enhance durability and color. Some treatments involving wax and oil are relatively harmless, while other methods—including dye, impregnation, and reconstitution—are more controversial.