Cutting Opals: Opal Lapidary Information - 1Earth Gemstones and Appraisals Magazine

Stop Press! Stop Press! Stop Press! The famous Virgin Rainbow Black Opal is for sale here! Cutting and polishing is the process by which the opal is completed before setting in jewellery. Uncut opals (opals in the rough) are often stored in distilled water; to reduce the chance of crazing. Once an opal specimen is taken out of the water its susceptibility to crazing increases. Cutting or polishing opals, especially opals from areas notorious for crazing (hot areas), is a risky business; often it is a matter of chance if the opals craze or not. To protect them from crazing, never wash opals with chemicals or detergents and avoid sudden changes in temperature or hot lighting.
Photo Tourism SA	Opals from Lightning Ridge, Australia
To Cut Opals A dop-stick is a short piece of thin dowel which is used as a handle. A rub is stuck onto the end of a "dop-stick" with jeweller’s wax. Using a fine grit cutting wheel, and holding the stone by means of the dop-stick, the stone is shaped and flaws and scratches are cut from the stone. The gemstones are then polished on a leather wheel using jewellers' polishing powder. Retain as much size and weight as is compatible with all other factors, such as overall appearance of the gemstone. During the cutting process, reassess the stone with each touch of the cutting wheel, checking on the appearance and colour and the presence of any faults, and to ensure that the maximum potential of the stone is achieved.
A solid light crystal opal from White Cliffs, NSW, Australia	Oval opals Oval shaped stones are still the most popular, but sometimes in order to achieve this shape, a lot of good opal may have to be cut away.
Free Form Opals In order not to grind away fantastic colour that has taken millions of years to develop, and to achieve the best possible size, an opal maybe left in the individual shape in which it was found. These stones are called "free-forms", and are becoming popular as people see how attractive and unique these stones look set in jewellery.
A free-form opal. Note the unique shape. Free-form opals are increasingly being preferred to traditional oval-shaped opals.	'The Red Heart of Australia' A solid black opal from Lightning Ridge
Another method of cutting free-form opal is to leave an undulating surface. Sand inclusions are removed, usually with a small drill, and the stone is then polished and set in jewellery. This method of preserving as much of the opal as possible, whilst still producing a very special and absolutely unique piece, is becoming more and more popular. A jeweller can use the full scope of his or her skills and imagination to set such a piece. Mounting, Assembled Opals Opal is sometimes impregnated with oil, plastic or wax to improve the play-of-colour and to prevent or disguise cracking. The plastic method is stable, but oil and wax are not stable. There are various techniques for creating the appearance of black opal, including smoke impregnation, backing with black or coloured paint and treatment with dye, silver nitrate or sugar carbonized by acid. Avoid repolishing or applying solvents to treated opals.