The size and number of these molecules as well as the ratio of silica to water determine the intensity, number and distribution of colors portrayed. Crazing will devalue the stone and is not repairable. Therefore, it is important to treat opals with care and respect. Harsh detergents and chemicals will not only strip the stone's luster, but will also dry it out. It is thus recommended that opals not be worn when doing dishes and laundry nor when swimming.
Opals are also quite soft and, if worn daily, are better protected in pendants and earrings.
They can be worn regularly in rings if the stones are set low and well protected with metal, however do avoid wearing opals during rigorous work or play.