Opal comes in many different forms from countries throughout the world. Australia has been the biggest producer for many years and includes boulder opal from Queensland, black opal from Lightning Ridge, crystal and white opal from Coober Pedy and crystal and matrix opal from Andamooka. The mining town of Mentabie used to be a major producer of dark based opal but has now been closed down by the state government. Other countries include Ethiopia which has become a major producer, Mexico, U.S.A. (Virgin Valley Nevada and Spencer Idaho), Brazil, Honduras and Peru.

Opal is an amorphous form of silica, chemically similar to quartz, but containing 3% to 21% water within its mineral structure. Gem grade opals usually have 6% to 10% water content. Opal is a sedimentary stone. Under the proper conditions, water percolates through the earth, becoming rich in dissolved silicates. When water enters a cavity, it deposits the silicates as microscopic spheres, forming opals. If the spheres are uniform in size and shape and neatly stacked, they will diffract light. These stones are called precious opals. If the spheres are random in size, shape, and arrangement, the results are common opals.

Opal is generally sold in 4 ways: 

Solids or natural stones are cut from pieces of rough opal thick enough to form cabochons. This type of stone regardless of origin is regarded as the most expensive form of opal.

Doublets are produced by cementing a slice of opal onto a backing. This is particularly common where opal is backed by natural ironstone and sold as Queensland Boulder Opal doublets. These doublets are sold at a fraction of the cost of equivalent solid opals and also provide matching pairs of bright colored opal that is difficult to do with solids.

Triplets are made by cementing a very thin slice of opal to a black backing and then covered by a quartz cap to simulate a domed cabochon.This is the least expensive form of opal.

Be aware that because of the glue used on doublets and triplets repeated dunking in water can cause the stone to become water-logged and cause the stone to fade or become milky in color. 

Rough opal is also sold in its natural form. After the opal has been trimmed and cleaned to seams with little or no potch it is then sold in parcels to interested cutters. The price of the parcels depends on the quality and volume of opal found and can vary dramatically.

In the metaphysical world opal helps create joy, optimism, creativity and amplifies joy and love. It aids intuition and is a stone for deep meditation. Opal brings to light our most negative thoughts and aids in letting them go while enhancing one’s positive emotions and helping to fulfill our greatest potential.Opal stimulates originality, creativity, memory and spontaneity. It reminds us that what we put out to the universe will be returned. 

By Neville Ryan

EarthGallery.com