Opal shapes and settings Opals can be cut into a wide range of popular shapes. Oval is by far the most popular shape, followed by the circular or round shape. Teardrop, square, rectangle, and triangle are other common shapes.
Most solid opals and doublets are cut and polished with a convex dome or curved top. This encourages light into the stone so that the opal’s iridescent properties are shown at their best. For triplets, the dome is created by a crystal cap that covers the flat slice of opal. Some opal cutters prefer to let the opal define its shape rather than imposing a shape on the stone. Opals cut in this manner assume unusual freeform shapes.
This ring is an example of where the cutter has followed the natural contour of the opal bar and has produced a stone with undulating shapes. A most unique effect and an example of the many and varied opal shapes and settings
Australian opal is rarely faceted, nearly always domed. A domed stone is stronger and less prone to chipping. However, opal without a play of color (such as cherry red or amber opal from Mexico) is often faceted and can look a lot like ruby.
Opal shapes and settings often depend on the initiative of the Cutter.
Opals are a carver‘s delight. The stone is not too hard to work with and will not wear out your diamond tools as much as such stones as chrysoprase, agate, or the like. Opals are a carver’s delight. The stone is not too hard to work with and will not wear out your diamond tools as much as such stones as chrysoprase, agate, or the like. This Koala
has been carved from a chunk of opaque white or milk opal from the Coober Pedy region in South Australia.
Opals are often calibrated to specific sizes to make the stones easier to fit into standard jewellery castings. The most popular calibrations are stated in millimetre (mm) measurements.
Click on the calibration chart to see an enlarged version of the gauges used for various shapes and sizes of cut opals. Use your Back button to return to this page.
Popular sizes are listed below. Sizes in bold type are more commonly available than other sizes.
Round: 5 mm and 6 mm
Oval: 6 x 4, 7 x 5, 8 x 6, 9 x 7, 10 x 8, 12 x 10, 14 x 10, 16 x 12, 18 x 13, 20 x 15, 25 x 18, 30 x 22, 40 x 30.
Opal Shapes and settings have to be taken into consideration when castings are made
Jewelry castings for opals can range from very simple designs to very ornate designs with accent diamonds.
Low Cost Findings (settings) these are available for opal cutting enthusiasts and are not expensive. They are a way of putting home cut stones into settings that can be sold as pendants with chains also provided. They can be silver, silver gold plated, gold plated over base metal.
There are some interesting myths associated with opal settings. Some folks believe that doublets and triplets are always put into fully backed settings to hide the potch backing. Others believe that full backings are used to protect the stone. Neither myth is true. A jeweler could just as easily “hide” a doublet in an open backed setting–as the join line between the stone and the potch backing would be covered by the side of the setting, making it difficult to see whether the back of the stone was a different stone or simply the less brilliant side of the same stone.