Faults and inclusions
A naturally mined opal may have some marks, potch (opal without colour) and cracks within the pattern. This affects the value of the opal but sometimes the fault is so small you wouldn’t notice unless looking under a magnifying glass. These obviously cannot be sold as perfect opals but some serious bargains can be picked up. They can still have beautiful patterns and a very bright lustre. GEM N I can sometimes offer these for sale at greatly reduced prices. All actual inclusions will be advised to customers on purchase. I am against selling cracked opals due to future problems.
Solid opals are made into cabochons, a term for un-faceted gems, unlike diamonds, sapphires, emeralds etc. The most common shape would probably be the oval. This shape is used a lot in ring settings. Teardrop is probably the second most common. These are sometimes used for pendants. Other shapes include circles, rectangles, triangles etc. Of course there are also opal carvings which can be spectacular and are ‘a real art in themselves’.
Opals are not the hardest of gems and care must be taken not to drop them on hard surfaces. They will sometimes break. Some from different opal fields are harder than others but as a rule, take care. Never put an opal near a naked flame or high heat as this could ruin it. The water content of opals is surprisingly high at around 6-8%. Having a shower or bath with it won’t hurt. It won’t make any difference to its properties as they are locked in by nature.
Just be aware that I am talking about solid opals!
If you buy a doublet be aware that they are made from a thin layer of opal with black opal potch backing or similar black stone, and in the case of triplets, there is an even thinner layer of opal with the potch, with a glass dome on top. These are stuck on and water will penetrate eventually, so keep them out of water!