The Opal: October’s Rainbow-Hued Birthstone

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If you celebrate a birthday in October, perhaps the most intriguing thing to know about your birthstone is that no two opals are alike. Opals capture the colors of other precious stones, creating a myriad of configurations and making each one truly unique. But that’s only the beginning. Let’s take a closer look at the October birthstone, which is also the national gemstone of Australia.

What Makes an Opal

Opals aren’t true minerals, but mineraloids, meaning that they lack a defined crystal structure. Opals form where rain and other water sources carry dissolved silica deep underground. When the water evaporates, the remaining silica forms into spheres of opal.

One interesting result of this type of formation is that certain things can become opalised – such as fossils. Perhaps the most famous of these is Eric, a complete pliosaur skeleton whose bones developed an opal sheen. Just as remarkable, explorers also found an opalised fish in its stomach (researchers named the fish Wanda).

As a result, the structure of an opal can consist of as much as 20 percent water. Consequently, many uncut opals are stored in water to prevent a condition called ‘crazing,’ in which the stone forms random internal and external cracks.

This internal structure is what allows an opal to refract a large amount of light, giving the stone its rainbow complexion. Depending on the makeup, opals can be primarily clear, white, red, blue, rose, yellow, slate, or very rarely, black.

Although primarily sourced from Australia, opals are also found in Brazil, Mexico, Ethiopia, Canada and in the U.S., primarily in Nevada and Idaho.

Forged By Lightning

Many superstitions have been attributed to the opal over the centuries. According to the Gemological Institute of America, Arabic lore states that opals fall from the sky in flashes of lightning, while the Greeks believed opals could grant prophecy and protection from disease.

In Australia (where 90 percent of the world’s opals originate), one legend of the country’s indigenous people is that the Creator descended to Earth on a rainbow, and where his foot touched the ground, the opal was born.

Other legends have claimed that opals can grant a carrier invisibility when wrapped in a bay leaf, or that the stone is a sign of death and bad luck. This attitude became popular after Sir Walter Scott’s novel, Anne of Geierstein, was published in 1829, in which a prominent character carries an opal amulet with supernatural powers (spoiler alert – she later dies when holy water is spilled on the opal).

If you’re celebrating your birth this month, be proud of your birthstone. Opals are unique and delicate, yet full of power.

Jeff Johnson & Co. is a full-service jeweler located in Upper Arlington, Ohio. We specialize in custom engagement rings, keepsakes for significant moments, and giving new life to family heirlooms. Our gemologists are trained by the Gemological Institute of America, and they work closely with each customer to ensure that we meet your vision and beyond. Stop by our showroom at 5025 Arlington Centre Blvd. (off Henderson Road), call 614-459-8890, You can also follow us on Facebook at Jeff Johnson & Co.