Coober Pedy Antique Opal Bracelet
"Pride of Australia" or sometimes called "Red Emperor"
Australian Gem Opal is a form of Silica chemically similar to quartz but not as hard on the Mohs Scale. Opal was first discovered in Australia near Angaston, in South Australia in 1849. Over 90% of the world's Opals comes from Australia.
Opal is formed as a result of a replacement of the organic material "wood" with opal. The replacement material is called Opal and consists of tiny layers of silica spheres structured in a regular pattern. Amber Gemstone is another organic gem and the result of biological processes, formed millions of years ago.
Guidelines for determining the price of Opals have been unsuccessful because of the stones infinite variation in color and pattern. The three main factors in fixing the price paid for Opals are:
Opals need attention just like other precious gems, ranked low on the Mohs Scale. However, don't kill your opal with kindness; less is more. Simply rinse Opals in fresh water to refresh them, without the use of harsh chemicals, detergents or abrasive cleaners. Use a bowl of water, not the kitchen or bathroom sink as you don't want your precious opal gem disappearing down the kitchen sink hole! Wipe your Opals with a lint free cloth.
Matrix Opal can be treated or "cooked" with a solution of sugar and then sulphuric acid to enhance the color (that tends to diminish in vibrancy over time). If the price looks too good to be true, it probably is!
Black Opal - Black body color with features of manganese oxide as host rock. See Aurora Australis Black Opal!
Crystal Opal - Transparent or very translucent.
Boulder Opal - Dark with iron stone as the host rock.
Milky Opal - Opaque. Mainly found in Coober Pedy, the Opal capital of the world.
Doublet - A composite of light natural Opal cemented together on either common Opal or base material.
Triplet - A composite of light natural Opal cemented to either common Opal or base material plus clear quartz or glass.
Synthetic Opal is produced in the laboratory and has a similar structure to that of precious genuine Opal. Gilson Opals are a good example of true synthetic Opals with colors that closely resemble a natural Opal.
The following observations though will differentiate between Opal gem and Synthetic or Faux Opal:
Synthetic Opal has numerous sub-grains that produce a distinctive "snakeskin" pattern.
Synthetic Opal has a more ordered pattern of colors (generally). The reason is because artificial Opal does not duplicate the complexity and intricate pattern of Natural Forming Opal.
"Aurora Australis" Image Courtesy: http://www.cooberpedy.sa.gov.au
"Gilson Opal" Image Courtesy: http://www.yourgemologist.com/syntheticopal.html
"Pride of Australia" Image Courtesy: http://www.opalsdownunder.com.au/learn-about-opals/introductory/famous-opals
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