Color : Colorless, white, yellow, orange, red, purple, blue, green, gray, brown, and black.
Hardness : 5½ - 6½

Opal is found in Western USA localities, Mexico, Australia, England, Czech Republic and many other localities around the world. It is the most colorful of all gems. The most desired and beautiful form of opal is black opal, which is opal with a dark blue, dark green, or black background with a strong play of color. Black opal is followed by white opal (opal with a light colored body color with strong play of color) and Mexican fire opal (transparent to translucent orange red color). Precious opals (black and white) are used in all forms of jewelry.