7.90 CT. MUTICOLOR IRIDESCENCE RIDGE BOULDER OPAL (NATURAL) 13.3 X 12.0 X 6.0 MM.

Opal

Modern birthstone for October

Opals can display a range of colors in what is called the play-of-color, or the streaks of colors they are so well-known for, created by silica spheres. Depending on the place of origin and color of the main body, opals can be differentiated fromDark or Black Opal, White or Light Opal, Milk or Crystal Opal, Boulder Opal, Opal Matrix, and also Mexican and Fire Opal. Opal variations are unlimited.

Most opals come from Australian mines. They are also mined in Mexico, Brazil, Ethiopia, West Africa, and some U.S. states, such as Idaho and Nevada. Opals are softer stones, and have a hardness of 5.5 - 6 on the Mohs' Scale of Hardness.

Opals can be up to 10% water and are quite fragile. They should not be allowed to dry out or be exposed to sudden changes in temperature. Many types of opals are enhanced by infusion of colorless oils and resins to improve durability and color. Doublets and Triplets use a thin layerof opal glued to a black base. Use a soft damp cloth to clean opals.