There are two main reasons why opals require special care. First, opals are relatively soft, with a hardness rating of 5.5 to 6.5 on the Mohs scale. This means that opal can be easily scratched, even by common dust (which typically contains particles of silicon dioxide with a hardness of 7). Second, most opals contain significant water content, usually in the range of 5-10%. This means that opal can dry out and crack or craze in a low humidity environment. Sudden changes in temperature can also cause opal to crack.
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| Opal from Ethiopia |
The best way to preserve your opal is preventive care. You can avoid scratching your opal by making a wise decision when you have it set in jewelry. Opals are best suited for pendants and earrings, where they are less likely to come in contact with hard objects. You can set an opal in a ring or bracelet, but a protective setting such a bezel is strongly recommended. An opal ring is really not suitable for everyday wear, but occasional wear rings are fine if you exercise care. Opal rings that are worn frequently will probably require repolishing after some years.
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| Black Opal from Australia |
Your opal should be cleaned on a regular basis. Use a mild detergent in warm water with a soft cloth. Avoid the use of bleach and chemicals, and never try to clean an opal in an ultrasonic cleaner, since the vibrations can cause cracking. If you live in a very dry climate or store your opal for long periods, you can keep it sealed in a plastic bag with a moisture source such as a damp piece of cotton. This will prevent dehydration.
Because opals are porous you should avoid contact with chemicals, cosmetics and household cleaners while wearing your opal. Opals should not be worn during physical activity such as sports or gardening.
Opals which have been damaged are difficult to repair, and current repair methods should be regarded as experimental. Most of these methods involve impregnanting the opal with polymers. Usually it is better to buy a new opal than try to repair a damaged stone, but it is worth trying to have a cracked opal repaired if it has special sentimental value.
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| Fire Opal from Mexico |
