Birthstone October - The Opal

Opal is one of two stones celebrated as the October birthstone, the other being tourmaline.

Opal is arguably the most unique, diverse, and beautiful birthstone. Unlike most gemstones, opal is amorphous which means it does not have a defined crystalline structure.

As you'll see from our own collection, it takes on many shapes and colours, adding that extra touch of mystery.  You can even find some that mimic the shades of autumn.

A little bit of history

Evidence of opal artifacts date as far back as 4000 B.C. The exact origin of opal's name is disputed, but historians are confident that in ancient Rome opal was known as opalus, which translates as the "precious stone." 

Not only has opal been in the minds and hearts of mankind for hundreds, if not thousands, of years, opals take a very long time to form. Though the exact cause of opal formation is still disputed, many believe that silica was carried down into rock crevices by heavy rains. Once the water evaporated, what was left was a silica gel that then hardened over the course of what some believe is millions of years.

A little bit of science

It takes roughly 5 million years to solidify just one centimeter of opal. This theory makes sense considering opal has water in it. The water content of an opal can be upwards of 20 percent but is usually in the 5 percent range.

There are two types of opals: precious and common. Precious opals either have vibrant colour (fire opal) or exhibit a play of colour. Play of colour is a term coined to describe the unique multi-dimensional colour display that the more precious opals have. Precious opals have two basic colours, their background colour and their play of colour. The background colour is caused by impurities within the silica. Within the precious opal family, there are many different varieties of opal. Each has their own unique colour combinations and character traits. Opals can be found in orange, yellow, red, green, blue, or purple, their colours caused by the way silica forms together. 

Opals that have the most intense and diverse play of colour are generally the most expensive and prized. "Boulder opal" is the only opal that can display the entire rainbow within one stone. That's at least seven colours if you count indigo. 

Black opals are considered one of the rarest gemstones, though they too can be a variety of dark colours.  Owing to the fact that opals often display a captivating interplay of various colours, it has also been known as the Queen of Gems. 

Unlike many other gemstones on the market, opals are usually left in their natural state. However, some common treatments include fracture filling and smoke treatment, which is used to darken the stone.

A little bit about mining and production

Since it is the place that more than 95% of today’s world supply of opal hails from, it is not surprising that Australia can boast several more completely unique varieties of this gemstone. This includes the white opal found only in several locations in the country, including Coober Pedy and White Cliffs; as well as boulder opal, which has the presence of ironstone to thank for its reddish hue, available only from one location in Queensland.

Other countries that commonly mine opals include Ethiopia, Brazil, Peru and Mexico - the latter being home to the highly prized variety of this stone, the fire opal. Ethiopia is known for its beautiful crystal opal which is transparent to translucent with little to no body colour and shimmering patches of play-of-colour. 

A little bit of folklore and symbolism

When it comes to the opal birthstone meaning and symbolism, the stone has been traditionally associated with loyalty, faithfulness, purity, hope and confidence. It is believed to be imbued with beneficial properties relating to vision, both in terms of eyesight, and internal visualisation, i.e. imagination and dreams. Some went so far as to claim that it could also bestow invisibility when properly used.

That is not to say that this stone didn’t have its own share of bad reputation as well. Aside from the fact that the opal was associated with the evil eye in Russian superstition, its popularity also received a heavy blow from a very well-read novel by Sir Walter Scott, published in 1829.

The novel featured an opal which cracks and becomes colorless when splashed with holy water, and ultimately causes the demise of its owner. The novel was so popular and its influence so great that it managed to put a significant dent into the sales of the stone for the next two decades after its publishing.

However, as superstitions waned and new deposits were discovered, revealing opals with colour schemes that were never seen before, the popularity of the stone recovered. 

10 fascinating facts about Opals

  1. In ancient times opal was included among the noble gems and was ranked second only to emerald by the Romans.

  2. Queen Victoria’s favourite gemstone was Opal! She had Sapphires, Rubies and Diamonds from all over the British empire but fell in love with the intoxicating colours of Opals.

  3. Until 1912, opal was considered the October birthstone. That year, the National Association of Jewelers released a modern birthstone list, which featured exclusively transparent gems. Thus, tourmaline replaced opal.

  4. Opals were particularly popular in the Art Deco era, when gemstone artists preferred them to all other stones.

  5. The Olympic Australis is the largest and most valuable opal yet found (as of 1961), valued at A$2,500,000. It was found in 1956 at the ‘Eight Mile’ opal field in the  mining town of Coober Pedy, South Australia.

  6. The Virgin Rainbow is one of the world’s rarest and most expensive opals. It literally glows in the dark.  It’s valued at over $1 million and was purchased by the South Australian Museum in Adelaide.

  7. Opal is softer than most other gemstones and best suited for use in earrings, brooches and other pieces of jewellery that rarely encounter scuffs and impacts. When used in a ring, the best designs have a bezel that fully protects the stone.

  8. Opal is the national gemstone of Australia.

  9. Opal is the second gemstone to be found in outer space. It was discovered on Mars in July 2015 by a NASA orbiter and one of the indications that there was water on the red planet

  10. According to research, it takes about five million years to solidify a single centimeter of opal.

Caring for your Opal

Due to its relatively high concentration of water (up to 30% in some stones), opal is much more susceptible to damage from heat or from sudden temperature changes. Because of their porous nature, opals are not to be cleaned by detergents or jewellery cleaners, as they contain acids and chemicals which might cause significant damage to the stone.

In order to ensure its longevity, you should clean your opal jewellery with a mixture of warm water and soap. Even then, try to keep the procedure as short as possible. Since opal doublets and triplets are held together by an adhesive, too much exposure to water can result in the weakening of the binding matter and serious deterioration of the stone.

Aside from being porous, opal is a relatively soft stone - a 6 on the Mohs scale of hardness. This makes it relatively prone to scrapes and abrasions and why we recommend keeping your opals separate from your other gems and in a cool, humid environment.