Frequently asked Questions
1. How is Boulder Opal different from the other types of opal?
The key defining feature of Boulder Opal is the rock. Because the opal has naturally bonded with the rock it is regarded as a solid opal. The other types of opal – black opal and white opal are seams of precious opal found in black and white common opal (respectively) which form in pockets in clay beds. In short, black and white opal is precious opal found in common opal whereas boulder opal is precious opal found in rock.
2. Are the opals in the Opal Art Scenic Range solid opals?
Yes. A solid opal is a natural opal. Because Boulder Opal is hosted by rock and the bond between the rock and opal is natural Boulder Opals are classified as solid opals.
3. What is the difference between a polytop finish and a traditional finish?
A polytop finish uses a polymer to seal the opal stone with a high gloss finish without requiring the stone to be sanded as thoroughly as per the traditional finish. A traditional finish requires the face of the opal to be sanded smooth in order to achieve a high gloss finish. This process can greatly reduce the scenic value of the piece as opal colour and rock patterns are sacrificed to achieve a smooth surface.
4. What is potch?
Potch is “common” opal and while it shares the same chemical composition as precious opal it lacks the ‘play of colour’ seen in precious opal.
Potch has the same chemical composition as precious opal but the molecules are arranged differently; irregular rather than regular (see section – What is opal?). Because of this, potch/common opal does not work with light in the same way. One of the good things about potch is that it is more abundant and therefore lends itself to dramatic specimens and scenic stones. Potch can be blue, white, grey, purple, caramel, or black, but usually only one or two colours at a time.
5. What is precious opal?
Precious opal is opal with complex colours and patterns and play of colour.. Precious Opal is gem opal.
6. How are opals graded?
Opal is graded on colour, pattern and size. Some colours are more rare than others hence the rarer the colour the higher the price. Generally speaking, red is the rarest colour, then green, then blue. However there are many variations of red, green and blue, and this makes it difficult to explain value and pricing. Opal prices reflect availability and demand. Experts who have worked with Boulder Opal over a long period of time set the value to meet the market.
7. What is a good opal?
It depends on the reason for purchasing – investment, enjoyment or both. The main thing is to know what you are purchasing. The type of opal and whether it is a solid, doublet or triplet are the two most important things to consider. After that it is subjective to the buyer. Boulder Opals are often cut in free form shapes and require a jeweller to hand make a setting around the stone. In this instance a buyer should consider how much gold or silver will be needed to set the stone as this may affect the decision to buy.
8. Are opals only found in Australia?
Australia produces 90% of the world’s opal. Australian opal is highly regarded for its diversity, beauty and stability. Opal is the national gemstone of Australia and is part of the land itself.
9. Is opal a birthstone gem?
Yes, Opal is the birthstone for October.