10 Interesting Facts About Opal
Opals are among the most mesmerising gemstones in the world. Known for their rainbow flashes and rich symbolism, they’ve sparked fascination for centuries. But beyond the shimmer lies a world of ancient history, rare geological quirks, and surprising records.
Here are ten fascinating facts about opals that show just how much more there is to discover about this remarkable gem.
The Romans Had a Poetic Name for Opal
The Romans were deeply enchanted by opals and gave them the name opalus, from the Greek opallios and the Sanskrit úpala, meaning “precious stone.” Some Roman writers also referred to opals with the nickname Cupid Paederos, describing them as being as beautiful as a child of love. The Romans associated opals with purity and hope, and considered them among the most valuable gems, second only to emeralds.
Queen Victoria Loved Opals and Changed Their Fate
In the 1800s, opals suffered a reputation crisis when a popular novel portrayed them as a stone that gave bad luck. Superstitions spread across Europe, and demand dropped sharply. But Queen Victoria helped turn things around. A devoted fan of opals, she often wore them and gave opal jewellery to her daughters, helping restore their popularity and charm.
Opals Are Formed by Ancient Rainwater
Unlike gems formed under heat and pressure, opals are created when water rich in silica seeps into cracks in rocks. As the water evaporates, it leaves behind layers of silica gel that slowly solidify into opal. This process can take millions of years and results in the delicate, layered structure that gives opal its unique play-of-colour.
Some Opals Form in Volcanic Rock
Most Australian opals are found in sedimentary rock, but Ethiopian opals form in volcanic rock, particularly rhyolite. These volcanic opals are often more porous, which can make them more sensitive to water and humidity, but their vivid colours still make them highly sought after.
Fossils Can Turn Into Opal
In rare cases, opal doesn’t just fill empty spaces, it replaces entire fossils. In Lightning Ridge, Australia, paleontologists have discovered opalised shells, leaves, marine creatures, and even dinosaur bones. One small plant-eating dinosaur, Weewarrasaurus pobeni, was found with glimmering opalised remains.
The First Synthetic Opals Were Created in France
French chemist Pierre Gilson developed the first lab-created opals in the 1970's with a structure that closely mimicked natural ones. These opals displayed real play-of-colour and had similar internal patterns, making them both a scientific and commercial breakthrough.
Harlequin Opal is Extremely Rare
The most prized opal pattern is known as “harlequin.” It features large, sharply defined blocks of colour that resemble a mosaic or checkerboard. True harlequin opals are exceptionally rare and can command some of the highest prices per carat in the opal world.
Lightning Ridge Produces the World’s Most Valuable Opals
Black opals from Lightning Ridge, in Australia New South Wales state, are among the rarest and most valuable opals on the planet. Their dark body tone creates a striking contrast that intensifies their play-of-colour. Top-quality black opals can sell for over $10,000 USD per carat.
The Fire of Australia Weighs Nearly a Kilo
The largest known polished opal is called the Fire of Australia. This incredible gem weighs 998 grams (4,990 carats) and comes from Coober Pedy. It's not just massive, it's gem-quality throughout. The stone has been valued at over $1 million USD and remains a national treasure.
The Most Valuable Opal Ever Found is Worth Over $2.5 Million
The Olympic Australis holds the record for the most valuable opal ever discovered. Weighing a staggering 17,000 carats (3.45 kg), this uncut opal is almost entirely gem-quality. It was found in 1956 in Coober Pedy and is estimated to be worth over $2.5 million USD.
Whether you’re interested in gem history, rare patterns, or curious geology, opals offer plenty to admire. From shimmering fossils to royal approval, this gemstone has a story like no other.