The Opal

I’ve always been a little afraid of opals. They’re temperamental: brittle, heat-sensitive, easily scratched. They contain water, and someone once told me they should be stored in damp cotton to keep them from cracking. (This is usually not necessary.) Oh, and it’s supposedly unlucky to wear opals if they’re not your birthstone. (Opals are October. I’m June: pearl, moonstone, alexandrite.)

Opals are wanton extroverts. Their glamour is unabashed and in your face. Even the quieter ones are Technicolor. There’s a physical reason for this. While most gems get their color from mineral impurities—rubies, for instance, are red because of the presence of chromium—opals contain actual rainbows. They’re composed of trillions of submicroscopic spheres of silica packed together like layers of Ping-Pong balls in a box, with water filling some of the empty spaces. When light passes through these silica layers—depending on how they’re arranged—it diffracts into the colors of the rainbow. Gaze into an opal, and suddenly you’re in Oz.

My Technicolor opal. Its colors are created by light diffracted through layers of silica spheres. Smaller spheres diffract blues, and larger ones diffract greens, oranges and reds.

I was certainly transported—though I wasn’t sure where—when I received the opal above as an anniversary gift. My husband bought it from a trusted wholesaler, knowing I’d want to put it in a less flashy setting. The stone was definitely flashy enough on its own; the diamonds made it look almost gaudy. I had no clue how I would wear such a thing.

The naked opal

So I scrapped the setting, the better to contemplate this mesmerizing black opal from Lightning Ridge in Australia, the country that’s still the most important source of gem-quality opal. Black opals are among the rarest and priciest, formed of darker material that makes the rainbows look brighter. This stone would make a fabulous ring if my hands were larger—and if I weren’t afraid of bashing it against something and damaging it.

A jeweler friend was also a bit spooked by the stone. She told me that opals are tricky to set. They’ll crack if you put too much pressure on them. Ditto if you apply too much heat. To minimize this risk, some jewelers use lasers instead of welding torches. Many are reluctant to set opals at all. We pondered. The stone remained unset.

My first Australian opal. The photo reveals a ding in the right-side prong, hinting that the setting process was not without incident.

I looked at my other opal, above, given me many years ago by my estimable husband. It’s light in color, like most Australian opals—mesmerizing in a softer way—and set simply, with prongs. I realized that even this can’t have been easy to accomplish.

I don’t want to make too much of this. Opals aren’t as delicate as all that. They’re slightly harder than glass, 5.5 to 6.5 on the Mohs scale. Like glass, they’re amorphous, meaning they lack a crystalline structure. Some kinds of opals are prone to crazing (internal and external cracking) if they’re allowed to dry out or exposed to vibration. But opals that make it through the cutting and polishing process are tough: they’re stable and unlikely to crack. Contrary to myth, they don’t need to be soaked in water, though if they’re stored in conditions of extreme dryness, a bit of damp cotton will help. Opals should not be cleaned with ultrasound, exposed to household chemicals or worn for hours in hot sun.

Some opals are practically indestructible. Boulder opals (above) are embedded in their host rock. They’re easy to set, lovely to look at, and not expensive.

Also inexpensive: opal doublets, where a thin slice of natural opal is glued to a black backing. Or triplets: doublets with a third, clear layer glued on top. These can be very pretty, but they need to be kept out of water, which can penetrate between the layers and fog them up. Doublets and triplets are not fakes, but they’re more manmade than natural. Besides, there’s a new, relatively affordable opal on the block.

Hydrophane opals from Ethiopia

The opals above are from the Welo district in Ethiopia, an abundant source discovered in 2008. Unlike Australian opals, which formed in seams in the rock of ancient sea beds, Ethiopian opals are volcanic and formed as nodules, some quite large. Volcanic opals are hydrophane, meaning they can absorb water. Soaking them for a long period can change their color or the way they refract light, but Welo opals will revert to their original state once they dry out, so they’re considered stable. There’s a ton of them on the market, at excellent prices. (You can read about other varieties of opal here.)

By the way: opals are not unlucky. They’ve been deemed both holy and unholy for millennia. The most recent myth began with an 1829 novel by Sir Walter Scott in which a Baroness wears an opal with supernatural powers. She crumbles to ash when a drop of holy water falls on the stone and drains it of its color. This novel pretty much killed the Victorian opal market. And yes, it’s by the selfsame author who indirectly triggered the craze for Scottish Victorian jewelry I wrote about in my last post.

My Lightning Ridge opal remained unset for well over two years. I wanted something that would show off its rainbows in an un-gaudy, diamond-free way, and it finally dawned on me that I knew who could do this.

Bezel setting in 22 karat gold by Reinstein/Ross

I took it to Reinstein/Ross, whose goldsmiths have set a lot of opals and aren’t afraid of them. Their setting, above, is handmade, with soft high-karat gold gently hammered around the stone. I love it. I can wear it.

And I’ve told my wonderful husband that I have enough jewelry and don’t need any more.


2 thoughts on “The Opal

  1. I love this ESPECIALLY Sir Walter Scott killing the market for opals. Have always adored opals, ever since I was a little girl and an aunt in Australia brought my mother some lovely opal earrings and showed me the light in their hearts. I love the pearly ones best, and used to have a ring once, but it left me long ago. But your greeny one is exquisite. ps I didn’t it was ‘need’ exactly that drove the acquisitions 😉


  2. Pingback: In lumina

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