Opal is a naturally-occurring amorphous solid known for its flashes of fire color. An amorphous solid is a material that, unlike crystal, is not organised in a regular lattice pattern. This makes for some unusual interactions with light, and is explicable for opal’s rainbow colours.
However, just because opal is classified as amorphous is not to say that its atoms are arranged without order. Chemists have discovered a clear sphere structure in opal, which has led to them copying it in 1974. Synthetic opal is often named Gilson opal, after Pierre Gilson, the man who invented it (along with a number of other synthetic minerals: coral, emerald, lapis lazuli, etc.). If you’re looking for someone to blame for having paid over the odds for a synthetic substance, by the way, Pierre Gilson is the man you’re looking for.
Originally synthesised in Switzerland, Glison opal is now primarily synthesised in Japan (by Kyocera and Inamori, for example). It differs from natural opal inasmuch as it is much more regular. Synthetic opal, though less desirable than organic opal in the eyes of most lapidaries, is not to be confused with imitation opal, which, unlike pure synthetic opal, is tinctured with minerals not found in actual opal. The term “Gilson opal” is usually used to refer to imitation opal, opals which are not only lab-created but contain minerals not found in actual opal (minerals such as plastic in Slocum stone, for example).
If you ever find yourself in the market for opals, you’d be well advised to bring a loupe along with you. Under a high magnification (of around sixty), it’s clear to tell by the regularity and columnar nature of the patterns that the opal is synthetic. Even to the naked eye, the columnar nature of the opal is plainly visible. With the help of a loupe you’ll be able to discern a so-called ‘lizard skin’ effect in the patches of colour. This crumbly surface is the most common “tell-tale” of synthetic opal.
Synthetic opals are said to fluoresce a green colour under UV light. Along with the loupe, you’d be well advised to take a UV torch along with you to the flea market (or wherever you go to get your opals). If it fluoresces, it’s synthetic; if not, it’s natural.
Synthetic opal comes in two main kinds: white opal and black opal. The white opal is generally more expensive than the black, largely because the white is more natural-looking than the black.
A new man made opal Monarch opal has recently come onto the market and many people think it isa new opal, but it is man made synthetic opal.
Monarch opal has been the most confusing man-made opal so far as dark black the potch line inclusions look like treated Andamooka stone
Another man-made opal is Aurora Opal made by the German company Pinfire Gems and Colloids
These Synthetic Opals and Synthetic Impregnated Opals, Coarse and Fine Crystalline Opals have a Non-Directional Play-of-Color and are seen in lot opal bangles. They market Aurora black opal, Fire opals and Crystal opals. The Aurora opal patterns are described as Irregular and non-directional swirls.
Bello opal by Sanwa a Hong Kong based company that makes synthetic opals as well as synthetic turquoise.
SYNTHETIC OPAL CHEMICAL COMPOSITION: SiO2.nH2O+Resin
Many countries manufacture opals as it is a valuable gemstone, so unfortunately we will be expecting more synthetic opals to come on line. To our knowledge China and Thailand are constantly trying to manufacture new products for this market to catch the unsuspecting opal buyer. Professional laboratories try and market their product as brand name.
Synthetic opal is available in sheets or blocks. Blocks are used to make bangles and sheets are ideal for inlay work or matching sets rings, pendant and earrings.
Warning to hobby cutters, most of these man made silica opals do have the same properties as natural opals, which can cause problems with lungs called silicosis.
Caveat emptor Buyer Beware!
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