Opals: Source, Forms, Value & Maintenance
Opals are increasingly becoming popular among a majority of jewelery lovers. But do you know where they come or how many forms they exist in?
Opal gemstones generally occur in specific geological conditions. Most are from the sedimentary environments around the Great Australian Basin. Politically they are located in NSW, Queensland and South Australia, which means the opals settle hundreds of kilometres from the main cities. A miner of the stones knows that he will have to spend days looking for opals before he can find even a single one.
So what is it exactly?
Opal is a form of silica very similar to quartz, but contains water within its mineral structure. It consists of small silica spheres that are arranged in regular patterns. It is popularly used to make contemporary opal jewelery. The colour comes from the diffraction of the white light breaking virtually to all colours of a rainbow. This play of the colour depends upon the angle of incidence of the light, and the colour changes when turned. The size and spacing of the spheres are also the cause of the colour alteration.
Exact origin and forms of Opals
As mentioned earlier, opals come all the way from NSW, Queensland and South Australia, but their exact location can be pinpointed in the town of Coober Pedy in South Australia and the Lightning Ridge at New South Wales. In fact, Lightning Ridge is the major source of black opals. The blackness of the opal can be determined by ignoring the colours and concentrating only on the overall body.
Another form of opal is the boulder variant. The name comes from an ironstone backing which is a part of its natural formation. The colours are very bright and vivid in this type of gem. Boulder opal is very expensive and competes in price with the black varieties.
Yet another form of this gemstone is the fire opal, which is transparent and found with a warm body, the colour of which ranges from yellow to orange. These gems don’t like to play with colours and are quite different from the rest. However, the most famous source of fire opals is outside Australia, in Mexico.
How to value them?
The price of an opal naturally depends upon the play of colour. It depends upon the shades themselves and the pattern of reflection. If an opal has flashes of red, its value will be much more than that of others. For overall evaluation, the thickness of the stone is considered with the appeal of the colours, cut, weight and finish. Before you buy an opal, check out the following:
- The play of the colours
- The brightness of the gem
- The body tone of the stone
- The saturation and intensity of the colours
- Whether the colours appear dull if viewed from different angles
- Whether it has a flat or rounded dome
- The weight and size
- The cut and shape
Caring for your opal jewelery
Avoid extreme changes in temperature that can cause the jewelery to crack. Make sure that it does not get hit by any hard material, and avoid scratching. Clean the gems in warm detergent water using a soft cloth or brush.
This incredible item on earth is a mesmerizing item of jewelery that can be a great gift for loved ones.