Opals are a beautiful natural gemstone and, as an owner, you would wish to maintain and enjoy it for many years to come. Contrary to popular belief, natural opals need very little care.
The best way to describe it, is to say that it is about the same hardness as a pearl. As such, wearing opals when gardening or doing other activities, where it could be knocked and scratched, should obviously be avoided.
Natural opal does have a relatively high water content, but there is no need to soak it at intervals or be concerned when washing one’s hands. There will be some interaction with the atmosphere, but it is very small and a natural opal is more or less impervious to harm from an external water source. The only thing which might have an impact are some types of dissolved chemicals.
The only exception to this are Welo opals from Ethiopia, which are a hydrophane form of silica, which absorbs and gives off water readily. This results in some temporary changes to the translucency and colour plays whilst doing so.
Also, doublets and triplets will sometimes have water penetrate the glued layers, which makes the stone cloudy. This is normally irreversible, so avoid immersion in water with this type of opal.
Opals should also not be placed in modern sonic cleaners…it may have no effect, but better to be safe than sorry.
In conclusion, natural opals will do nothing but give you years of pleasure if worn as dress jewellery.
Virtually the same rules apply as you would give to any other expensive piece of jewellery.
Regardless of gemstone type, if abused, damage is likely to occur. Common sense, cleaning with a soft cloth and warm soapy water is all that will normally be required.