October’s birthstone is opal. If Boom was asked to pick her absolute favourite gem opal would likely be the winner. At Metal Studio, Boom designs with two very different types of opals. Australian opals which come in deep shades of blue and green and often range into a nearly black base color, and Ethiopian opals which are are more opaque and have deep red and orange and yellow fire along with more subtile greens and blues.
The name opal comes from Greek Opallos, meaning an observable change. In this case the color of the gemstone changes color and had deep and dramatic flashes called fire as the gem moves into different light spectrums and the light reflects out of the gem at different angles.
Opals form a little differently than most gemstones as well. Liquefied silica gel can seep into cracks in various types of stone and in the cracks it will form deposits of the gems. Because of this, in very rare cases opals can be the fossilizing material in natural specimens. These specimens, including wood, bone, tooth, shell or entire plants and animals are extremely rare and valuable.
When purchasing opals it is very important to keep some basic care guidelines in mind. Opals are a very soft gemstone and can be damaged easily. More care should be taken with opal rings than would be taken with other gemstones. Opal jewelry should be removed before manual labour, sports or any activity that could subject the opal to a bump or knock as this can crack or shatter the opal.
Opals, especially opaque Ethiopian opals are very susceptible to environmental conditions. A gemstone that is nearly perfectly clear in dry weather can turn a deep yellow or milky white in more humid climates. This does not damage the gemstone in any way and it will return to its natural color when the climate dries again.
Some jewellers recommend storing opals in a glass of water to preserve the color. While this won’t do the gemstone any damage we do not recommend this practice for jewelry as it can damage the jewelry. Australian opal doublets can also have the substrate they are attached to damaged by storage in water. If you would like to preserve the integrity of opals a small shot glass of water can be placed into your jewelry box for storage with the opals. This will keep the humidity at a more consistent level but this is not a necessary step for storage of opals.