Precious Opal and Common Opal
Opal is made from Silica and water. It is a non crystalline material. Opals are found in several countries around the world. I frequently get people from Russia and Africa wanting to sell me very large quantities of opal but the opal they want to sell me is one color and has very little appeal to me as we can get poor colored opal every day of the week in the Lightning Ridge area of NSW in Australia. We call it potch and it is what is termed common opal. Common opal has no color variation. It may be a dull looking blue or green or gray or white but it has no play of color.
Precious opal is what everyone is searching for. Precious opal has a play of color. Sometimes we call it fire. When you turn a piece of cut and polished opal around in your hand the play of color will be evident. As you move it around the colors change and will go from bright flashes of one color to different looking blasts of other colors.
It was formed mostly in regions which were inland waterways millions of years ago. As these areas weathered silica seeped into groundwater and gradually settled into dried out spheres which cannot be defined even with an ordinary microscope.
Precious opal will be different from one piece to the next. It is rare to find it possible to cut matching pieces from one chunk of opal stone. I have cut many large pieces and couldn’t find two small pieces that I could match into a pair of earrings. That is the beauty of precious opal it is not common and no two pieces are likely to be the same.
Precious opal can be found in many parts of the world but Australia provides about 95 percent of all precious opal mined. It is mined in many parts of Australia but the two types that are recognized as being the best are black opal and white opal. There are sub types of these two such as crystal. Boulder opal is also recognized as precious opal.
It is precious opal which makes the best opal jewelry. Common opal is still useful for making beads and ornaments and low priced jewelry. Precious opal is often just bought by collectors and stored away as pieces for investment and pleasure.