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Solid Boulder Opal   
Solid boulder opal
A solid boulder opal is an opal that is natural and unchanged or untreated by humans. solid meaning the opal has not been enhanced or attached to anything else in any way. Some opal that is man made is called boulder opal doublets where the opal color has been glued onto the boulder host rock to look like an opal solid but is not. A great way to tell the opal is natural is to look at the edge of the stone with a loop or magnifying glass to see if their is a glue line or a straight line of color. This doesn't mean that opal can't have a straight line between the top and the bottom because it can. So looking very carefully will help you in your decision. If you not sure take it to an opal dealer and they will tell you straight away.
Boulder opal comes from Queensland in Australia and is formed in a host rock called ironstone. The ironstone is type of rock that shade from light brown to dark brown in color and will usually be the backing for the opal when it is cut and polished. Sometimes you will get the opal so thick that no backing is needed so they will make a crystal, but this is rare.
Polishing boulder opal can be tedious and messy. Usually boulder opal has undulating faces where the opal cutter has followed the seam through the host rock. These cutting machines are smaller and different form using normal black opal cutting machines. They need to be more rounded to get into the curves and concave that boulder opal can produce. Splitting a solid boulder opal is quite easy to do. All you need is a slicing machine to make a small cut in the edge of the seam of color, just big enough for a flat head screwdriver to fit into. The all you do is twist the screwdriver and the boulder should easily split in two. Most boulder seams have natural faults going through the color and all it takes is for as little pressure to slip the opal into 2 faces. This can make magnificent natural boulder opal pairs.
As boulder opal is found more and more the value and supply will grow. The expanse opal mining fields here in Queensland are mostly untouched and the boulder opal boom has not hit yet.
For more information on opal cutting or purchasing opal. Please email blackopalsdirect@live.com or you can call me on Skype My username is Blackopaldirect and it's free!
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