Octobers Beautiful Birthstone: The Opal

The only gem known to man whose rainbow fire can surpass that of even the diamond, opals have long been a popular, revered and somewhat lesser expensive alternative to diamonds and are today widely used to create exquisite jewelry items. They also happen to be the stone which celebrates the month of October. As such, there is no better month than this to take a closer look at what makes opals so exciting and one of the worlds most colourful gems.

The Opals Origins

Despite the fact that in 2015, opals are mined in numerous locations within Australia, the United States of America and Mexico, the opal is most famously associated with Australia. In fact, the national gem stone of Australia is the opal and the country itself is home to some of the most famous opal deposits in the world, as well as producing some of the worlds most valuable opals. To this day, Amooka and Coober Pedy, both regions in South Australia, provide some of the worlds most perfect conditions for naturally forming opals due to the conditions created by the Great Artesian Basin which underlies 22% of the country of Australia, which translates into a staggering 1.7 million km squared area and is populated by a massive 200,000 human population.

Opal Formation

Opals are formed via a rather simple yet astonishing recipe that of water and silicon dioxide. When water trickles and runs through the earth where sandstone is most abundant, it collects deposits of the silica found within that stone. The silica it collects along its way is then left behind in small pools and puddles in nooks and voids created by fossils and cracks in the soft sandstone. As the water evaporates, it leaves in its wake small silica deposits. As the process repeats the deposit grow in size and harden to form opals.

Opal Lore

According to Ancient Greek mythology, opals were believed to have formed as the calcified tears wept by Zeus after the titans were defeated a battle which saw Zeus reclaim his brothers and sisters from within the stomach of his father, Cronus and then defeat his father to himself become the king of all gods. Hence, the spherically formally formed opal which can indeed appear to look like a dew drop or water drop, whilst the distribution of its silica create an almost mystical glitter effect came to symbolise Zeuss victory.Meanwhile, it is long established in Indian lore that the opal is the result of the Goddess of Rainbows having wilfully turned herself to stone to avoid the unwanted romantic advances of other gods. Hence, the pieces of rainbow contained within opals were said to be proof that the stones were deposits of the Goddess herself, and this is perhaps how the opal came to represent purity and innocence.

Opal Variations

The wealth of variation in the colours, hues, translucency and size of opals is vast. The conditions through which an opal is formed determining its eventual appearance, the most common opal is that of the potch opal which bears an almost milky or pearly lustre referred to as opalescence.

Other types of opals used to create jewelry include black, fire, boulder, crystal precious and jelly opals. What unites all opals is the unique way in which the silica contained within these mineraloid creations creates a rainbow affect. It is precisely the fact that opals have a mineraloid structure, unlike a mineral structure (hence, crystalline structures such as diamonds) that results in opals having their signature rainbow fire.