Types of Opals
Peruvian Opal: is a gem-quality type of “common” opal. Common meaning that is lacks the “fire” found in Australian opals. Peruvian Opals range from beautiful blues and greens the color of salt water in tropical seas to lovely pinks and peaches that you see as the sun starts to set. Many of the darker hued stones are cut to include some surrounding matrix providing a color interplay of translucent color with veining or backing of warm browns.
Boulder Opal: are easily distinguished by their layer of solid brown ironstone left on the back of the stone. Boulder opals, as the name suggests, are mined from large ironstone boulders under the ground. Thin veins of colourful opal forms in cracks and fissures in these boulders. Because these veins of colour are so thin, opal cutters need to leave the ironstone on the back of the opal to form a full sized stone. The thin layer of opal in boulder opals can display any colour of the spectrum.
Care and Cleaning: Different types of opals require different cleaning methods. To determine what kind of opal you have, look at it from the side. At an angle, you can tell if it is a solid opal or if it’s made up of layers. A thin slice of opal glued onto a backing is a doublet opal, while two layers with a clear cap on top is a triplet opal. If layers are not apparent, then you have a pure opal.
Use a mild soap solution to clean the stones. Place 1/2 cup of warm water into a small bowl. Be sure the water is just warm, as both hot and cold water can crack opals. Add two or three drops of mild, unscented dish soap and create lather.
Pure opals can be placed directly into the cleaning solution for a few seconds and then swished around to remove any dirt on the surface. You should then carefully rinse it, as soap can dry it out if left on the surface.
Doublet and triplet opals, on the other hand, should be carefully cleaned with a microfiber jewelry cloth that has a bit of the cleaning solution on it. You must rinse them using the same method of wiping with a jewelry cloth.
A microfiber jewelry cloth or other very soft cloth can then be used to dry the opal. Dry it as thoroughly as possible, as water can be damaging to these gems.