What Is Opal - Gemstone Facts and Information

| 18 min read

Is any gem prettier than Opal?

With is scintillating play of color and sheer range of hues, William Shakespeare's 'queen of gems' is one of the most beautiful stones ever discovered. Its fascinating history stretches back thousands of years and brings us right up until the present day, with significant deposits of the gem still being made around the globe.

Here, we take a closer look at the history and science of the Opal, as well as some of the wonderful varieties we're able to source for you here at Gemporia. We hope you enjoy this brief history of Opal - let's get started...


The name Opal has long been thought to have derived from the Latin word ‘Opalus’ meaning ‘precious stone’, and the Greek ‘Opallios’ meaning ‘to see a change in color’. However, these two words are themselves derived from the older Sanskrit word ‘upala’.

This word dates back to around 250 BC, at which point it was thought that Opal was more valuable than any other gemstone in the world. Archeologists have dated early Opal finds to over 10,000 years ago in North America and 6,000 years ago in Kenya. This latter discovery was thought to be Ethiopian in source, as Ethiopia borders Kenya to the north. Both of these deposits must have been forgotten by Roman times however, as before major discoveries in Australia in the late 19th century, the only noted source was in Cervenica, Slovakia.

Opal Infographic

Opal was long thought to be the most precious of gems because it harboured the colors of many other revered gemstones. Fine quality specimens will shine with a whole rainbow of hues that bring to mind many other sought after jewels. Roman scholar Pliny the Elder (23 - 79 AD), who wrote about many of the gemstones he encountered, mentioned Opal in his Natural History encyclopedia.

He said:

"In the Opal you shall see the burning fire of the Carbuncle or Ruby, the glorious purple of the Amethyst, the green sea of the Emerald and all glittering together, mixed after an incredible manner. Some Opals carry such resplendent lustre with them that they are able to match the bravest and richest colors of painters: others represent the flaming fire of brimstone, yea and the bright blaze of burning oil."

At this point in history, the word Carbuncle was most likely referring to very good quality red Garnet.

Opal Jewelry Selection

This eye-catching gem has weaved a path through history, leaving an impression on many cultures and civilisations across the globe. Fire Opal was discovered in South America at least 6,000 years ago and was coveted by the indigenous peoples. The Aztecs worshipped the gem and named it ‘quetzalitzlipyollitli’, meaning the ‘stone of the bird of paradise’.

In Ancient India and Ancient Persia, Fire Opal was admired as a symbol of ardent love; Ancient Greeks saw the stone as a talisman that protected against disease, and Arabian legends tell a story of how Opals fall to earth from the heavens during lightning storms.

Multiple European countries have held Opal in high regard not only for its beauty, but for its purported ability to strengthen the virtues of purity, hope and truthfulness.

The Romans delighted in the colors of Opal, using the gemstone as a way to boast about their wealth and status, and they sourced their Opals from mines beyond their borders in eastern Europe. The Roman general Mark Antony wanted to give Cleopatra of Egypt an Opal as a mark of their relationship, and approached a fellow general, called Nonius, with an offer to buy his impressive stone. Rather than sell it, Nonius fled Rome and left behind his home and most of his possessions. He got to keep his Opal, though!

Opal was so valuable to the Romans that one Roman Emperor is said to have offered up one third of his entire kingdom in exchange for a single stone. William Shakespeare mentioned Opal as ‘a miracle’ and coined the term ‘queen of gems’ in his play Twelfth Night, which he wrote between 1601 and 1602. The French emperor Napoleon offered a reported 700 carat Opal to his first wife Josephine, known as ‘The Burning of Troy’ because of its vibrant red flashes. Whilst the stone is so well documented that it is generally accepted to have been a real gem, it sadly hasn’t been seen or heard about since Josephine passed away in 1814.

For all the positive attributes associated with Opal over the years, there were some negative ones too. Opals can dry out if they’re not treated with care (read on for Opal care and cleaning), and this can lead to the stone going dull; in extreme cases, Opals can also crack, known as crazing. Before the science of Opal was fully understood, this dulling and crazing led many to conclude that Opal was a harbinger of bad luck.

Indeed, Opals have been considered both good luck and bad luck throughout history. They were as precious as Diamonds to the Ancient Greeks and used in jewelry by the Romans, whereas in Russia the Tsars considered the stone to symbolise the evil eye. When Europeans first went to the New World they found the Aztecs of South America mining the gem, and due to its rareness and beauty they took many back to Europe to be presented to the royal courts. By the early 19th century, the bad luck associated with the stone had gotten somewhat out of hand, and Opal had fallen almost entirely out of popular use.

Thankfully, later in the century, Queen Victoria threw aside any talk of misfortune and superstition that had become ingrained in the story of Opal and started to wear the gem. Queen Victoria was something of a trendsetter, and her loyal subjects often looked to her for inspiration when it came to fashion and jewelry. She helped popularise the stone once again, and put to rest any negative connotations the gem was still carrying.

Opal was found for the first time in Australia during the 1840s, and high-quality Black Opal was discovered there in 1877; then, as the 19th century became the 20th, Australia kept adding new deposits to the map. Opal mining began in Lightning Ridge in 1905, Coober Pedy in 1915 and Andamooka in 1930. All these deposits, and more, are located in a large area of Australia known as the Great Artesian Basin. The basin covers over 22% of the whole country, and in very simple terms it's essentially made up of very porous rocks that hold a lot of moisture, an essential ingredient in the formation of Opal.

Over 90% of the world’s Opals were coming out of Australia until very recently, when phenomenal-quality Opal was rediscovered in Ethiopia, first in 1994 and again in a different location in 2008.


Opal is one of the birthstones for October (along with Tourmaline) and is the gemstone given on a 14th wedding anniversary. The characteristic bright colors given out by Opal are caused by tiny amounts of moisture and silica trapped within the stone. Alongside Diamond, Sapphire, Ruby and Emerald, some jewellers include Opal as the fifth precious gem. You only have to take a single glance at a top-quality stone to see why they would collectively bestow it this rare honour.

Whether you class it as precious or semi precious, Opal is one of the most popular and sought-after gemstones that we’ve ever sourced.

Coober Pedy Opal pendant

Opals are gorgeous gems, with the most beautiful Opal specimens containing every color of the rainbow. Their unique internal colors are one of the most fascinating visual effects created by nature, a phenomenon referred to as ‘play of color’. Opals are doubly attractive as they often also have a beautiful iridescence, known as opalescence.

The incredible play of color witnessed in gem-quality Opals is caused by the refraction of light. The body of each Opal is made up of tightly packed silicon balls with moisture and solidified acids trapped in the gaps between them. Light enters the gem, bounces off the curved surfaces of the silica and is emitted back out of the gem. Depending on the size of the silicon balls, different colors will be refracted - for example, silicon balls 0.2 microns wide will refract blue light, silicon balls 0.25 microns wide will refract green light and silicon balls 0.32 microns wide will refract red light.

Opals formed from hydrated silicon dioxide were created when water-based silica solutions deposited gel-like substances in gaps and crevices in rocks. They are often found around areas where there are hot springs or geysers. This natural process actually occurs reasonably frequently, but often the resulting stone is a lacklustre ‘common Opal’ with its atoms arranged randomly within the stone, meaning there is no crystal structure. Common Opals also come in a variety of different base colors, but often have little or no play of color. Gem-quality Opals do, however, have a neatly arranged crystal structure and almost always have a play of color.

Boulder Opal earrings

Opals are loved for their kaleidoscope of colors and internal flashes of light. There are several varieties of gem-quality Opal, and the names used for them by the gemstone industry can be quite confusing. When you hear about White Opal, Grey Opal (also known as Semi Black Opal) or Black Opal, the names are referring to the background color of the Opal (sometimes known as its matrix or host rock). Think of this as the canvas on which the beautiful colors are displayed. Even once set into jewelry, Opals still contain moisture, and this can vary between 3% and 20% of the stone. Because of this, Opals are considered to be a relatively soft stone, measuring between 5.5 and 6.5 of the Mohs scale.

Common Opals can be found all over the world, whereas gem-quality Opals are mostly mined in Australia. Some reports claim that 97% of the world’s gem-quality Opals are sourced from here, though the more recent discoveries in Ethiopia (in 1994 and 2008) are starting to make their mark on the industry. Not all Opals are opaque, and there are other body colors available too. Fire Opal, for example, displays vibrant yellows and oranges, while Mali Opal is green, and Peruvian Opal is pink.

Opal jewelry

Boulder Opal consists of fine layers of Opal which have formed naturally on ironstone rock. Much like Ammolite, it is removed from its host rock while it is being cut and then placed back on to it. This means that for most Boulder Opal, the finished gem is actually a doublet or triplet, and Boulder Opal from Queensland is declared by many experts to have the most brightness and best appearance of the Australian Opals. Sometimes beautiful quality Opals can form naturally, but in fragile layers that would never survive day to day wear in jewelry. When these thin slices are taken and strengthened with ironstone later, we call this Crystal Opal on Ironstone.

The 2008 discovery in Ethiopia isn’t the only new Opal source of the last few years. One of the best discoveries recently has been Pink Opals from Peru. Gem hunters the world over are always looking for naturally-colored pink gemstones - it's one of the most desirable colors, and provides a real feminine touch to jewelry.

The Pink Opal we sourced from South America is stunning; we also came across a trader in Mali, who we already had a relationship with as a Garnet dealer, who had unearthed an opaque green gem. Visually it resembled Jade, which is uncharacteristic for this area - and sure enough, the laboratory tests confirmed that it was, in fact, Green Opal! We named the discovery Mali Opal, after its origin.

We also once sourced a single parcel of Yellow Opal from Tanzania, although sadly have been unable to source any further gemstones, despite our very best efforts.


Gemstones are as old as time and, in the years since their first discovery, they've picked up a lot more than adoring collectors and fascinated mineralogists. Many have gained stories regarding their legend, lore and healing properties, and whilst there's no evidence to suggest that any of these properties are real, it's still interesting to explore the esoteric side of Mother Nature's miracles.

It's worth asking ourselves, "If you truly believe in something, does that mean it's true"? Scientifically, the answer is no, but what about on a more personal, spiritual level? If you really truly believe that an item in your house is having an effect on you, are you more likely to feel that effect? It's really not for us to say, but it's a very interesting concept that deserves further research.

Once again, though, we must point out though that no studies have ever found any therapeutic effects or properties in gemstones, and the following is for your information only.

Opal has been revered throughout history for the explosion of color trapped within, and this rainbow of different hues has bought a wide array of associations to the stone. Hope, happiness, love, luck and innocence have all been linked with Opal, as have creativity and optimism. The stone has been thought to help bring ones repressed negative feelings to the surface, helping to purge them. Each individual type of Opal also carries its own meanings, with Fire Opal being linked with artistic expression and Crystal Opal with intelligence and joy.


  • Color White, grey, black base with a rainbow of color flashes (plus many other varieties)
  • Family Mineraloid
  • Mohs Scale Hardness 5.5 - 6.5
  • Specific Gravity 1.88 - 2.45
  • Refractive Index 1.39 - 1.46
  • Lustre Vitreous to resinous
  • Crystal System Amorphous
  • Transparency Transparent to opaque
  • Chemical Formula SiO2·nH2O
  • Composition Hydrated Silica


Opal mine map

Where do Opals come from? Well, Australia has been a world-class source for Opal since the mid-1800s, with considerable mining operations in Lightning Ridge, Coober Pedy, Mintabie, Andamooka and others too. It has been joined more recently as a major supplier of the stone by Ethiopia, with major discoveries in 1994 and 2008, most notably in the Welo (also known as Wollo) area. The mine at Wegal Tena is unusual as it's 300 metres below the cliff top, and the miners climb and abseil down to the seam, then mine into the cliff face.


Coober Pedy Opal

The Coober Pedy gem mines, situated 526 miles north of Adelaide, are unique. The vast majority of the miners who work in this area, which is known as the 'Opal Capital of the World', live underground. Rather than building a house on the surface, where the temperature can become terrifyingly hot in the summer, most miners choose to build their homes in their mines where it is considerably cooler. It’s not uncommon to find a three bedroom home, with a full kitchen and bathroom, some 20 to 30 metres below the surface of the earth. The Australian government prefers to allow small independent artisanal mining rather than large scale operations, and therefore grant each prospector a plot of less than a few hundred square feet. Over 200,000 independent shafts have been dug here since the gem was first unearthed in 1915, further contributing to the unusual nature of this mining community.

The formation of these high-quality Opals took place around 120 to 160 million years ago. This occurred during the break up of the supercontinent Gondwana, when the landmasses we now call Australia and Antarctica became separated. It’s hard to imagine it today, with its desert heat and intense dry atmosphere, but this part of Australia was once a huge lake, under which the Opals formed.

Crystal Opal On Ironstone

The popularity of Opal continues to soar around the world, and sourcing Opal from Australia in particular has never been more difficult. Many generations of miners have made their fortunes at Coober Pedy by digging their way down to the Opal seams and retrieving stones from gem-rich pockets that run underground. This has resulted in a lot of spoil heaps of discarded dirt on the surface - or at least the miners thought they were spoil heaps.

As it happens, Crystal Opal can form inside otherwise unremarkable stones, so by checking back through the rocks in these piles of dirt, secondary miners have been able to yield a wonderful quality of Opal that forms in very thin slices. In order to bring this wonderful play of color to our jewelry designs, the thin slices of colorful Opal have been mounted on Ironstone from Queensland to strengthen them and significantly increase their longevity. The dark background significantly adds to the effect, and helps the explosion of ancient color trapped within these Opals really pop.

Ethiopian Opal

We often think of gemstone discoveries as ancient tales that have been lost to time, but this wonderful quality of Opal was only discovered in 2008. Opals from the Wegel Tena mines in the Welo province of Ethiopia are so high grade that they often surpass the quality of those found in Australia and Brazil. The play of color witnessed in many Wegel Tena Ethiopian Opals is stunning; the gems range in transparency from opaque to transparent, and a high percentage (more so than at other famous Opal sources) are Jelly Opals. The body color is normally whitish, however sometimes it can appear a magical bluish color and occasionally can be discovered as a honey color.

The play of color tends to be slightly dominated by red and orange flashes, but some exceptionally rare pieces demonstrate all of the colors seen in the rainbow. The Wegel Tena mines are all located very high above sea level at an altitude of 3,200 metres. Any budding mountaineer would love these deposits, as they are found in a horizontal layer of ignimbrite rock that runs 30 metres below the top of a an exposed cliff face! We've visited the mine and made a documentary about it - click below to see it:

Ethiopian Opal Mining Ethiopian Opal

American Fire Opal

For decades, the very best Fire Opal was mined in Mexico, and indeed the country still produces wonderful quality stones. But in 2014, Gemporia was contacted by two gentlemen called Chuck and Ken who were recovering incredible Fire Opal stones from a deposit in Oregon, USA. So excited by the material he was seeing, our founder Steve Bennett flew out to meet the men and see the mine for himself. The quality of the gemstones coming out of this mine was so good that Steve immediately bought the entire run of the mine, something that has only happened a handful of times in our whole history.

What Steve saw was that no two stones were the same, and that they were all shimmering with the colors of the most glorious sunsets. The gems featured no defining hue, and instead, each stone had a different tone and character - a very rare find indeed. Our expert gem cutting team unlocked the potential of each rough gemstone by allowing as much light to enter each stone as possible, bringing out a full palette of warm yellows, golden oranges and subtle reds. These American Fire Opal pieces offer a very different look in Opal, and are a must-see and must-own stone for any collector.

American Fire Opal

Ethiopian Opal rough


Opals are beautiful, but particularly delicate when it comes to cleaning. Warm soapy water is still the best method, but don’t submerge it in the water. Some Opals are doublets or triplets, where the Opal has been combined with another gem or even a synthetic material to strengthen it for use in jewelry - therefore, soaking in water can eventually cause these layers to separate. Instead, moisten a soft, lint-free microfibre cloth and buff the gem gently. Use a dry part of the cloth to remove any moisture that remains. Opal doesn’t like sudden temperature change, so use room temperature water, and avoid ultrasonic and steam cleaners with all Opal.

Jewelry Cleaning Methods


Keep Opal well away from any extreme heat sources as they contain a small amount of moisture. If this dries out your Opal, it can look dull and may start crazing. If you fear your Opal is losing moisture, sometimes wrapping it in moist (but not soaking) cotton wool and putting it in an airtight bag can help. Check it regularly, and re-moisten the cotton wool if it has dried out.

Opals react badly to acid and alcohol, so be especially careful to keep them well away from any household cleaning products, aftershaves and perfumes, etc. The gem is 5.5 to 6.5 (out of 10) in hardness on the Mohs scale, so keep your Opals well away from other jewelry and always store them in a box or soft pouch when not wearing them.

Jewelry Boxes


The beauty, softness and multiple pin-flash colors of Opal make it an extremely sought after gemstone, and Gemporia is proud to source this rarity from some of the world's finest sources. Whether you're looking for a classic Opal ring, a dainty pair of Opal earrings or a bold and brash Opal pendant, our designers have crafted the perfect piece for you.

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