The Enchanting World of Opals: Fire, Color, and Myth

Rough Mexican Opal

Image: Géry PARENT, Public domain, via Wikimedia Commons

The Science Behind the Sparkle: Gemological Facts

Opal is a hydrous form of silica (SiO₂·nH₂O) that contains 3–21% water. Unlike crystalline gemstones, opal is amorphous, meaning it has no defined internal structure. The microscopic silica spheres arranged in an orderly grid give opal its unique brilliance. When light passes through, these spheres diffract it into a dazzling spectrum, creating the phenomenon known as play-of-color.

Hardness: 5.5–6.5 on the Mohs scale
Refractive Index: 1.37–1.52
Specific Gravity: 1.98–2.20
Transparency: Transparent to opaque

This structure makes opal both fragile and vibrant—a truly alive gem with light.

Coober Pedy Opal Mines in Australia. 

Image: TalShiar at Dutch, Public domain, via Wikimedia Commons

Where Opals Are Found

While found across the globe, Australia is the undisputed heart of opal mining, producing over 90% of the world's precious opal. Major sources include:

• Lightning Ridge, New South Wales: Home of the rare and valuable black opal, prized for its dark body tone and vivid color play.
• Coober Pedy, South Australia: Known for white and crystal opals.
• Andamooka, South Australia: Source of the famous Andamooka Opal, gifted to Queen Elizabeth II.
• Queensland: Famous for boulder opal, where veins of opal form in ironstone.

Beyond Australia, Ethiopian opals are known for their fiery brilliance, while Mexican fire opals radiate warm reds and oranges. Opals are also mined in Brazil, the United States, and Honduras.

Rough Black Opal

Image: Tony Hisgett from Birmingham, UK, CC BY 2.0, via Wikimedia Commons

Types of Opal

Each type of opal has its own unique charm. Precious opal displays a play-of-color, while common opal does not. Here are the types of precious opal:

• Black Opal: Dark background with vivid color flashes; the most valuable type.
• White Opal: Pale or milky body with soft pastel hues.
• Crystal Opal: Transparent to semi-transparent with strong play-of-color.
• Boulder Opal: Layers of opal are naturally embedded in an ironstone matrix.
• Fire Opal: Typically orange to red, with or without play-of-color; mainly from Mexico.
• Ethiopian Opal: Known for high transparency and brilliant flashes, but hydrophane (absorbs water).
• Matrix Opal: Opal speckled within host rock, creating intricate natural patterns.

Crystal Opal

Aisha Brown, CC BY-SA 2.0, via Wikimedia Commons

The Magic of Play-of-Color

The dazzling play-of-color is opal's defining characteristic. Light diffracts through its silica spheres, creating flashes of color that dance across the gem's surface, a type of pattern that depends on how those spheres are arranged:

                                                Pinfire/Pinpoint                      Harlequin/Mosaic                               Flash

                                                                           Flame                                                          Peacock

• Pinfire/Pinpoint: Tiny, glittering dots of color.
• Harlequin/Mosaic: Checkerboard or mosaic-like pattern—rare and highly prized.
• Flash: Bold, sweeping color fields.
• Flame: Sweeping bands or streaks of red that move across the stone, similar to how fire moves.
• Peacock: Vivid flashes of blue and green, sometimes with other colors like purple, that resemble a peacock's plumage

Each opal is a unique natural masterpiece—no two are exactly alike.

Coober Pedy Precious Opal

Image: Dpulitzer, CC BY-SA 3.0, via Wikimedia Commons

Opals in Mythology and Lore

Opal's history spans thousands of years and many civilizations.

In ancient Rome, opals were associated with purity, hope, and love. Pliny the Elder called them "the union of the finest qualities of the most precious gems." Romans prized opals above all other stones, believing they combined the virtues of every color. 

In Greek mythology, opals were believed to have formed from Zeus's tears, his victory over the Titans, bestowing foresight and protection on those who wore them.

Arab legends said that opals fell from the sky in flashes of lightning, capturing celestial fire within.

During the Middle Ages, opals were seen as good luck and symbols of invisibility. They were believed to make their owners invisible if wrapped in a bay leaf.

In modern times, opal remains a cherished talisman of creativity and inspiration. It is also the birthstone for October, representing hope, truth, and emotional expression. Those born this month are said to possess the same iridescent spirit as the gem — colorful, luminous, and endlessly unique.

Australian White Opal Cabochons

Sevenopal, CC BY-SA 4.0, via Wikimedia Commons

The Anne of Geierstein Curse—and Why Opals Are Not Bad Luck

The idea that opals bring bad luck is a literary misunderstanding that began in the 19th century. In 1829, Sir Walter Scott's novel Anne of Geierstein featured a tragic heroine who wore an opal in her hair. When a drop of holy water touched the gem, its colors faded, and she soon died. Readers mistook this dramatic plot device for truth, and opals were unfairly branded as ill omens for decades afterward.

However, history tells a different story. Queen Victoria adored opals and wore them constantly, gifting them to her daughters and popularizing them throughout the British Empire. Her influence effectively restored the opal's reputation, transforming it from a supposed "cursed stone" to one of "enduring beauty and elegance.

Today, gemologists and collectors celebrate opals for what they truly are—symbols of creativity, passion, and transformation, not misfortune.

The Flame Queen Opal.

Image by David Plane c/o Wikipedia

Famous Opals in History

• The Aurora Australis: Discovered in 1938 at Lightning Ridge, this 180-carat black opal is one of the world's most valuable.
• The Olympic Australis: Found in 1956, it weighs over 17,000 carats and remains the largest and finest uncut opal ever found.
• The Andamooka Opal: Gifted to Queen Elizabeth II during her first visit to Australia in 1954.
• The Flame Queen: A remarkable "eye-of-opal" displaying "concentric color rings, discovered in 1914.
• The Burning of Troy Opal: Once owned by Empress Joséphine, famed for its intense red flashes.

Caring for Opal Jewelry

Opals are fragile and require gentle handling and storage to maintain their beauty.

Care & Maintenance Tips:

• Avoid harsh chemicals: Remove opal jewelry before using cleaners, perfume, or hairspray.
• Mind temperature changes: Sudden shifts can cause cracking or "crazing."
• To keep the humidity stable: Store in a padded box or fabric pouch; a small, damp cloth nearby can help prevent dehydration, which leads to "crazing."
• Clean gently: Use only mild soap and a soft cloth or toothbrush—never steam or put in an ultrasonic cleaner.
• Choose protective settings: Bezels or halo designs offer extra protection for daily wear pieces.

With proper care, opals can remain as luminous and enchanting as they were the day they were discovered.

The Eternal Allure of Opals

From ancient myth to modern artistry, opals have always symbolized imagination, mystery, and individuality. Their otherworldly play-of-color captures the essence of creativity—constantly changing, yet timelessly beautiful.

At The Gemmary, we celebrate the opal's enduring appeal through our curated collection of antique and vintage opal jewelry, each piece hand-selected for its quality and character. Whether you're drawn to soft pastels of a Victorian white opal brooch or the deep cosmic hues of a Lightning Ridge black opal ring, every opal tells a story that's as unique as its wearer.

Explore our opal collection at The Gemmary and find a treasure that glows with the fire of legend.