Opal is a unique and beautiful gemstone which will last indefinitely if properly cared for. Generally speaking, you should treat your precious opal with the same care and respect as you would with any other fine jewellery.
While there are some special requirements, caring for opal is very simple if you keep in mind two basic facts about opal.
Firstly, most precious opal contains about 6 - 10% water. Therefore opal can craze or crack when subjected to harsh, dry conditions and rapid changes of temperature.
Secondly, opal has a hardness of about 5.5 to 6.5 measured on the Mohs' scale of hardness. Compared to this diamonds are harder at about 10, garnets, the same at about 6.5 and gold is much softer at about 2.5 - 3. Therefore, opals like any other gemstone can be broken, chipped, scratched, or lose its shine with heavy wear and tear.
Danger areas for your opal jewelry are bathrooms and kitchens with tiled floors where it can drop onto the floor and damage the opal. Another one is your jewelry box where the opal is left in contact with harder gemstones like diamonds and sapphires which can easily scratch your opal. When not wearing your opal jewelry or traveling with it, always carry it in a soft cloth! A tissue can be used, but remember tissues usually end up in the trash can and could be the tragic end to your fine opal.
If you are not wearing your solid opals for a prolonged period, please leave it in water. Opals absorb water very easily. For doublet or triplet opals, it is not advice to do so. Your opal jewelry will need occasional cleaning. Use a soft toothbrush and a little toothpaste and lightly scrub it in lukewarm water.