Few gemstones are prettier and more mesmerising than Opal. Its history dates back centuries, and its natural play of colour is world-renowned.

Here, we look at Opal’s majesty in more detail. 

OPAL: GENERAL INFORMATION

Alongside Tourmaline, Opal is the birthstone for October. It is also the gemstone gifted on a 14th wedding anniversary.

Opal has long been considered the most precious of gems due to its many colours. Fine-quality Opals can display all the colours of the rainbow through their unique opalescence, and these scintillating hues are caused by tiny amounts of silica and moisture trapped inside the stone.

Opal has also been used as a symbol of status and wealth, particularly by the Romans, and is sometimes referred to as the fifth precious gem alongside Diamond, Emerald, Sapphire, and Ruby.

CHEMICAL PROPERTIES OF OPAL

Crystal System Amorphous

Specific Gravity 1.88 - 2.45

Refractive Index 1.39 - 1.46

Chemical Formula SiO2·nH2O

Composition Hydrated Silica

WHERE DOES THE NAME ‘OPAL’ COME FROM?

The name ‘Opal’ is believed to come from the Latin word ‘Opalus’, which translates to ‘precious stone’, and the Greek word ‘Opallios’, meaning, ‘to see a change in colour’.

However, both ‘Opalus’ and ‘Opallios’ derive from the much-older Sanskrit word ‘upala’, which again means ‘precious stone’. The word ‘upala’ dates back to around 250 BC, and at this time Opal was thought to be more valuable than any other gem on Earth. 

WHERE IS OPAL SOURCED?

Opal can be found all over the world, from Kenya and Europe to the USA. However, its most notable sources today are arguably Australia and Ethiopia.

Opal was first discovered in Australia in the 1840s. Since then, new deposits have been continuously discovered in areas like Lightning Ridge, Coober Pedy, and Andamooka. Each location is found in one large area known as the Great Artesian Basin, which covers over 20% of Australia’s surface. The basin is full of very porous rock which holds a lot of moisture – an essential ingredient in the formation of Opal.

Over 90% of the world’s Opal supply came from Australia until recently when a fine-quality deposit was rediscovered in Ethiopia in 1994 and 2008. Coober Pedy and Ethiopian are two of our most popular Opal varieties, so let’s look at them in more detail.

VARIETIES OF OPAL

Coober Pedy Opal

Coober Pedy Opals formed more than 120 million years ago, when the supercontinent Gondwana separated to become what we now know as Australia and Antarctica. Coober Pedy is now a desert; however, at one stage, this part of Australia was a vast lake under which high-quality Opals formed. 

The Coober Pedy mines are over 500 miles north of Adelaide, and due to soaring temperatures, most miners who work there live underground.

The miners at Coober Pedy find it much cooler 20-30 metres below the Earth’s surface, and most of them choose to build their homes there. This makes the Coober Pedy mining operation unique, and the mining area is made up of hundreds of thousands of independent shafts! 

The Australian government prefers small, independent mining to large-scale operations, and grants each prospector a plot of land measuring less than a few hundred square feet.

Ethiopian Opal

Opals are sourced from multiple locations in Ethiopia; the first discovery was made in 1994, and another deposit was unearthed in the Welo province in 2008.

Opals from the Wegel Tena mine in Welo are so high-quality that they often surpass those found in Australia! These gems have a miraculous play of colour and offer a range of transparency from transparent to opaque. Interestingly, a significant portion of the Opals found in this mine are known as Jelly Opals. Their body colour is usually white, but it can sometimes appear blueish.

Unlike the Coober Pedy mines, Ethiopia’s Wegel Tena mines are located high above sea level, at an altitude of over 3,000 metres. They are found in a horizontal layer of rock that runs below the top of an exposed cliff face, a perfect location for climbers and mountaineers!  

LEGEND & FOLKLORE

Like most gemstones, Opal has existed for much longer than we can fathom, so many legends and metaphysical associations are attached to it. There is no scientific evidence to suggest these stories are true; however, the metaphysical properties of gemstones are a fascinating topic that should be discussed.

Many countries around Europe and the world have put Opal on a pedestal for both its beauty and its supposed properties. Many believed the gem had associations with purity and hope, and Arabian legends tell of how Opals fell to Earth during lightning storms.

Due to its unique explosion of colour, the stone’s associations are varied; some link the gem to happiness, luck, love, innocence, optimism, and creativity, and others believe Opal has the power to purge negative energies.

Throughout history, Opals have been considered both good and bad luck. The Ancient Romans and Greeks believed the gem to be as precious as a Diamond; however, the Tsars thought it personified the evil eye and kept clear of it. 

HOW TO CLEAN YOUR OPAL

Because it contains moisture, Opal is one of the softer gemstones, measuring between 5.5 and 6.5 on the Mohs scale of hardness. It is suitable for jewellery, but it is also delicate and requires more care than stronger stones like Diamond and Sapphire.

Due to their softness, warm, soapy water is still the best cleaning method, but the gem should not be submerged in water. Moisten a soft, lint-free cloth and gently buff the gem. Always use room-temperature water, as Opals react badly to extreme temperatures. Ultrasonic and steam cleaners must also be avoided. 

HOW TO CARE FOR YOUR OPAL

If not treated with care, Opals can dry out, lose their colour and, in extreme cases, crack. This is known as ‘crazing’ and occurs when the gem is exposed to extreme heat sources.

So, always keep your Opals away from extreme heat; if you fear your Opal is losing its moisture, the stone can sometimes benefit from being wrapped in moist cotton wool and left in an airtight bag. If you choose to do this, always ensure to check it regularly.

As with all gemstones, keep Opals away from harsh chemicals such as cleaning products, lotions, and perfumes, and store them in a separate box or pouch when not in use. 

Opal is a unique gemstone with a glittering appearance and an even more fascinating history. To add this opalescent gem to your collection, shop for your next Opal at GemCollector.