Opal Introduction and Formation
Precious Opal is a gemstone. The word opal comes from the Greek word “Opallos” meaning to change colour. It is the only gemstone known that has the unique natural ability to diffract light.
Opal is estimated to have begun formation during the Cretaceous period (65-140 millions years ago). Central Australia was an inland sea in millions of years ago. As weather conditions changed and the sea gradually disappeared, the sand sediments released large quantities of soluble silica, creating a gel. This gel seeped into cracks and crevasse in the ground and gradually hardened to form opal.
Opal is composed of silica spheres that are packed together. In precious opal, the arrangement of spheres is an orderly three-dimensional grid. Light passing through the transparent spheres is scattered by the array of voids. White light is diffracted and split into its various colours at different angles.
Different Types of Opal
Precious opals usually contain 6-10%water. The water content of opal is easily lost if the stone is heated, causing it to crack or craze and to lost colour and/or clarity. Opal can absorb fluids, and should not be brought in contact with detergent or oils.
Doublets or Triplets are not recommended to be immersed in water. There is a special bonding cement hold the opal slice in place. Although this cement is designed to make the Doublets or Triplets waterproof, care should be taken. Please remove your opal jewellery before entering a shower, especially in hot water.
Violent impact with hard surfaces will cause defects on your opal jewellery. It is recommended to store opal jewellery separately from other jewellery. Always use a soft cloth to clean and polish your opal jewellery and do not expose it to high temperature environment.