Koroit Opal refers to Opal that comes from a particular area in Queensland. They are famous for their deep, strong ironstone with stunning patterns and inclusions of colour. They are also generally larger-sized Opals and are considered the best value for money Opal available.
The Koroit Opal Field was discovered in 1897 by Lawrence Rostron, who was a manager of a local property. He formed a group of eight and after many years of hard work they created the large Glasgow syndicate which was know as the Scottish & Australian Opal Mines.
The state of Queensland, Australia is home to Koroit Boulder and Matrix Opals. Nearby, the Opal-mining fields of Jundah and Opalton produce Matrix Opals, with thin colour bars that result in beautiful patterns. Blackgate Opal Field has produced some dark stunning Matrix Opal, also known as Aboriginal Art Opal.
Polished conglomerate Opal slabs from Koroit make stunning displays with their unique and beautiful natural patterns and kernels. Most often Koroit Opal is cabochon cut, with unique patterns and colours in each.
In recent times Koroit Opal has become popular not only because of its more affordable price but because of its diversity. Jewelers are using it in pendants, earrings, rings and Koroit Opal Beads & Strands.
Koroit Boulder opal rough needs experienced cutters to work the veins that appear in this rough and some miners sell 44 gallon drums that have to be worked.
The veins are tricky to follow and many cutters use saw to cut and split the boulder rough and colours can be spectacular with all colours of the rainbow.
A split is when miner has cut piece boulder rough and sees good vein of colour, he will put nick along this vein colour with his saw blade and the rock will split open revealing the opal colours. Sometimes it looks like both pieces have been polished so splits are popular in making earrings as very hard to get 2 pieces of opal matching in colour.
Ironstone from Koroit has interesting pattern so unique to this region, sometimes no or very little colour but miners call this black n white and patterns are so interesting and good natural look.
These thin colour bars need good cutters with experience and new cutters can easily rub the opal colour off with incorrect opal cutting equipment or sharp diamond wheels so best practise at your local lapidary club before cutting good opal rough
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