Turquoise is an opaque blue-green color and is the official birthstone of December. It is also used for the 11th wedding anniversary.
Turquoise is only found in a few places on earth. The color of Turquoise comes from a reaction of copper-rich water with phosphorus and aluminum minerals. Turquoise is currently the most valuable of opaque minerals used for jewelry on the market.
Ancient Egyptian jewelry found from 4,000 B.C. containing Turquoise makes it one of the oldest forms of gemstone used for jewelry or decoration. Some records go back as far as 6,000 B.C. making Turquoise a valuable gemstone for over 8,000 years. The Native Americans used to believe that Turquoise was parts of the sky that fell to earth.
Mineral Group: Turquoise
Refractive Index: 1.610 to 1.650
Birefringence: Not Detectible
Specific Gravity: 2.76 (+0.14, -0.36)
Mohs Hardness: 5 to 6