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What is rough crystal Opal?
Crystal opal rough is the natural form of opal extracted from a mine. Like all other opal rough it takes some cutting and polishing to highlight the play of color.
Most of the worlds precious rough opal comes from Coober Pedy in South Australia. The name Coober Pedy is an aboriginal term for ‘white man down a hole’. This type of opal has a light body tone as opposed to black opal which has a dark or black body tone.
It can be both translucent and opaque
Rough crystal opal is often milky white in appearance if it is opaque but if it is more translucent it is classified as crystal. As with all opal, the cutter just has to take a chance and make a cut to see whats there. All the time hoping not to cut across the face of the best part of the stone. For this reason, the opal cutting process with crystal or white opal often starts with the grindstone which removes some of the rubbish first before attempting to chase the color. Although the milky white opal in itself isn’t considered precious , it has a wide appeal to many and has been used very successfully to make beads. In recent years it has become rarer like most opal and is in great demand.
Cutting and Polishing Rough Crystal Opal
Crystal opal rough undergoes the same cutting and polishing techniques as all other rough opals. General cutting is done with a diamond slicing machine and then shaping takes place on a diamond grinding wheel as the cutter chases the color The final part of the process is polishing. The opal cutter uses progressively finer sandpapers until right the end he changes to a leather wheel with Cerium Oxide to bring out the final polish.
A lot more information about the opal cutting procedure is found in our special section on opal cutting. The ‘opal for the ordinary bloke’ CD (now updated with the new title “Opal, An Australian Adventure” will give you over 30 years experience of the opal industry as well as some really good tips on how to save money on opal cutting machinery. This extensive eBook is available freely for visitors to the Opalmine site but we do appreciate your support with the purchase of rough opal as soon as you are ready to develop your hobby or business.
Some opal collectors like to keep the cut and polished opal as a specimen, while others much prefer to wear it in the form of jewelry.