Last week, a good friend and I were discussing the possibility of Wings making a special piece using opal. It’s an unusual stone, one that, to use our recent metaphor, sort of straddles the beaten path and the grass next to it — another “gem” that some people don’t regard as a “stone” at all (others do; it becomes in part a question of semantics). And since I had both the mineral data to hand and (frankly more important, in terms of time constraints) certain photos at my fingertips, I took it as a sign that we should explore this stone a little further today.
I admit to being partial to opals personally. By some forms of reckoning, it’s my birthstone, and it’s frankly one that’s far more beautiful, and far more suited to my own personality and tastes, than the one found in most contemporary birthstone charts. Some of the best opals are also alive with an intense and fiery spectrum of shades, particularly the blues and greens that are my favorite colors.
So is opal a stone, or isn’t it?
Our answer is yes.
The confusion really seems to arise with conflation of the word “stone” with the word “mineral.” Some use the terms interchangeably. Others understand the word “stone” to encompass both minerals and non-mineral (i.e., “mineraloid”) rock material. And opal is classified as a mineraloid: an inorganic material that has no internal crystal structure. In this case, it’s a form of silica (which of course is known colloquially as “sand”). Specifically, it’s a hydrated amorphous variety: In other words, a noncrystalline substance that contains a substantial amount (by percentage of volume) of water. The “amorphous” label applies to naturally-occurring mineraloids like opal; to materials that may either occur naturally or be man-made, like glass; and to wholly synthetic substances like some films, gels, and polymers.
At any rate, despite its lack of a crystalline structure, opal manifests as a stone, and in fact occurs with other types of stone. When left in the host rock, it’s known as “boulder opal” (like boulder turquoise, which we’ve encountered here before, it appears in chunks or ribbons or sometimes mica-thin sheets of matrix inside other chunks of rock), and we’ll see some examples of it shortly. It also sometimes occurs as a pseudomorph, another phenomenon we’ve seen here before. A pseudomorph occurs when, over eons of time, the body of a once-living being breaks down and eventually disappears. Through heat, pressure, water, and/or other elemental forces, rocks and minerals surrounding its resting place push their way into the ensuing gap in the shell or bone, eventually replacing the body of the creature that once animated it with a stone or mineral that assumes its shape and form. With some forms of turquoise, it’s not uncommon to find old “clamshell” pseudomorphs, as the mineral pushed the desiccated interior of long-dead clams from their ancient shells, in the process, taking over their telltale shape. On the Wikipedia page for opal, it’s possible to see a [dark, not especially clear] photo of an opal/dinosaur bone pseudomorph: The gem filled cracks and crevices in the fossilized backbone of an ichthyosaur, and the specimen is now displayed to public view in the South Australian Museum. In fact, the museum has a collection devoted to opal fossils, what it calls “Rainbow Bones.”
Opal varies substantially in appearance, and there are differing grades of quality, as well. Mineralogists tend to distinguish between so-called “common opal” and “precious opal,” but in actuality, the line is a bit blurred. As I said above, opal does not have a crystalline internal structure, but that does not mean that it is lacking in structure at all; the internal structure of opal diffracts light, which is what gives the gemstone that fiery, flashing effect of a rainbow of colorful light inside the surface of the stone. Which colors appear depend on the type and quality of the opal, which range from nearly entirely to translucent to black, with stops at most points of the spectrum between. That said, there are some major categories.
Translucent opals are known as water opals (or sometimes “jelly opals”). Some appear largely clear, and you can see through them, for the most part, but they are not wholly lacking in color. Soft whorls and bands of white and gold and pale green and blue are common, giving the stone an almost agate-y effect. Wings once made a cuff with a Peruvian water opal, about seven years ago, and I have rued our failure to get a photo ever since. It sold to the first customers who walked through the gallery door on the morning we put it out for sale.
Still, that’s not what comes to mind for most people when they think of the word “opal.” Until some twenty years ago or so, the version of the stone most common to gemological use was the milk opal (sometimes called “milky opal” or simply “white opal”). And this is the form where the line between common and precious loses focus. There is a form of low-grade white opal that does not possess the requisite internal structure for real light diffraction, and so there is no interplay of color in the stone; it may not look precisely opaque, but it is simply milky-white. Opal miners (mostly from Australia, which is the world’s largest geographic source of the stone) refer to this low-grade form of opal as “potch.”
That said, there are milk opals or white opals that do diffract light, that exhibit a wide, if much more subtle, variety of color, and thus qualify as “precious opals.” Sometimes the stones’ overall color ranges from nearly snow-white to a creamy pale yellowish shade, and it is sometimes difficult to see the color variation without holding the stone up to the light. Still, the diffraction is present, and these were the stones most often found in mainstream dominant-culture opal jewelry until the two to three decades. The ring shown immediately above at right is an example of one of his older pieces made with a milk opal: very, very pale, but not potch; held to the light, pastel bits of fire were still evident. The cabochon in the Warrior Woman pin at the top of this post is an example of the sort of opal that straddles the threshold between milk opal and opals of other colors; it may have been simply an unusually fiery milk opal, or it may have been an exceedingly light-colored blue or green version of the stone.
Since that time, Australia’s opal market has boomed, and the rest of the world learned exactly what gifts of the earth lay in the ground of Oz. It’s common to see a variety of labels used: “black opal,” “blue opal,” “green opal,” “rainbow opal,” “fire opal.” Some of these are really only colloquial names, and some are misnomers entirely. In our own part of the world, there was a time when the ordinary label for virtually any non-milk opal was “black opal,” which disregarded the fact that there actually is such a thing as a black opal. Those black opals whose surfaces diffract with flashes of red are exceedingly rare, and are generally regarded as the most valuable opals in the world.
When lay people used the term black opal, more often they referred to the brilliantly-hued opals that manifest mostly in shades of blue and green. These are the opals for which Australia is now well known: fiery stones in deep, intense colors that resemble translucent sapphire and emerald, but displaying bits of white and yellow and pink and even red flame inside. Some also mislabel these stones “fire opals,” but fire opals, like black opals, are a specific variation, and they manifest in shades of scarlet and orange and yellow with flecks of blue and green, an inverse of their more common counterparts. Fire opals are also found in Mexico and South America.
Finally, there is a specific form of boulder opal that has its own name and its own niche market: the Koroit opal.
The Koroit opal comes solely from Australia. It derives its name from the Koroit Opal Field in South West Queensland, where the stone is mined. The fields, in Paroo Shire, share a name with a town in Australia, but the town of Koroit lies elsewhere, in the western reaches of rural Victoria Province. The opal field is some 300 kilometers wide, and consists of brownish sedimentary rock with small bits of opal matrix scattered throughout.
Koroit opals are unique in appearance: Brilliant flashes of mostly blue and green fire appears in small clumps and patches and long silken ribbons, contrasting starkly with the taupe-brown host rock — host rock that, when polished, nonetheless possesses its own nearly opalescent, slightly pearlescent sheen. It’s a beautiful dichotomy, and an increasingly valuable one: Wings acquired several Koroit opal cabochons a few years ago, and they continue to appreciate steadily in value. You can see a more vivid example of a Koroit opal immediately below, set into a pendant that he made for himself and then strung on old-fashioned copper-colored rondel beads.
Discussions of relative value bring us to cost generally. Unfortunately, opal is now an incredibly expensive gemstone: small natural milk opal cabochons that a few years ago might have been an option, if guaranteed to make the resulting work a bit pricey, now run several hundred dollars apiece just for the cabochons — and that’s
cost. And these are not the high-end stone, either; these are still largely free-form cabs that are whitish-yellow in overall color and without much fire or color inside the stones. High-grade opal? Nearly impossible for the average Native artist (or non-Native jewelry artisans, for that matter) to find via ordinary sources, much less to afford from any source.
And so, jewelry artists today commonly turn to a couple of other options: “lab opal” or “triplets.”
We’ll take the former first. “Lab opal” is exactly what it sounds like: wholly synthetic, wholly man-made “opal” manufactured in a laboratory, so to speak. Being synthetic hasn’t rendered them exactly cheap, however; the price tag on lab opal cabs is high enough that it’s easy for artists to assume, absent adequate information, that they’re getting lower-grade versions of the real thing. Wings acquired some many years ago, made a few small items with it, then learned what it really was and got rid of the remainder. Once you know how to identify it, it becomes relatively easy to spot: the matrix pattern is far too uniform. Real opal diffraction occurs in random-ish patterns, but lab opal is largely consistent. An example appears immediately above at right.
Triplets are something else entirely, and these are something Wings does use, if sparingly. We’ve talked before about doublets and triplets and their special meaning in the world of gemwork. A doublet is a small slice of a gemstone that is affixed to a backing to b
uild it up sufficiently into cabochon size. It’s used for either of two purposes (and sometimes, both combined): when the stone is so rare and pricey that only the thinnest slice is affordable; and/or when the stone is so fragile that it must be stabilized with substantial backing. Triplets are created for the same reasons, but with triplets, the fragility is virtually always a factor: a fragile, thin sheet of the stone is cut, affixed on backing made of some sturdy material (usually a man-made composite), and then coated with a clear, translucent cover of resin to protect the surface from breakage. It also has the added benefit of building up the cabochon in height so that it will rise above a bezel properly. In this case, the stones are built up, expanded in size and bulk, with synthetic materials (or at least via human intervention), but each cabochon contains the genuine gemstone. When Wings uses triplets, we clearly indicate that that is what they are when they are put up for sale. You can see an example of an opal triplet in the right hand of the Warrior Woman pin above at left. This stone was made with a slice of blue opal, but one so translucent that it nearly resembled a water opal.
Triplets reportedly are also sometimes made wholly of natural materials (save, presumably, the adhesive the binds the layers together). Wings is currently working on a piece for some friends who provided an opal cabochon from their old home in Idaho, which is one of the rare American sources of the gemstone. The opal that comes from Idaho tends to occur mica-thin sheets and to be especially fragile, and so often requires triplet treatment. Our friends bought this particular cabochon from one of the local miners who does his own cutting and cabbing, and he told them that the triplet in this instance is formed of three natural layers: a basalt backing, the slice of opal itself, and a clear quartz cover in lieu of resin. It will no doubt be a bit more fragile than those made with composition backing and resin covers, but it’s a beautiful blue-green stone.
Beyond the Koroit opal cabochons, Wings has only a couple of natural opals in inventory right now, and the friend I mentioned at the outset has spoken for one of them. The light in this shot is deceptive; in this iteration, they look pale milky-white; in another shot, they appeared deep lagoon blue. The reality is somewhere between the two.
At first, I nearly didn’t remove them from their protective bags, having assumed they would be lab opals from years ago that got overlooked. I’m glad I checked anyway. They’re clearly too random in diffraction pattern to be lab opals, and their very fire is much more natural-looking. They’re not triplets; there’s no backing. It’s unlikely in the extreme that they would be doublets with a synthetic top half instead of a backed base. As you can see, they’re very, very small — tiny, in fact. But they are truly beautiful (and one is now off the market, reserved for our friend).
Opal has no specific symbolism within our traditions (although it may for some other tribal nations). Since most of the world’s opals come from elsewhere — by far the vast majority from Australia, a smaller percentage from Ethiopia, and still smaller amounts from parts of North and South America — it’s more likely that spiritual and cultural significance would attach to them for the indigenous peoples of Australia and Ethiopia. Still, ancient trade routes like the Great Silk Road made them known to cultures in Europe, Asia, and the Middle East, and they make occasional appearances in old stories from various other regions, as well. Indeed, the word itself is generally attributed to a Sanskrit root: upala, usually translated as “precious stone.”
There is Hindu origin story that reportedly tells of a virgin goddess, one who represented the rainbow, who was pursued by two male gods. A mother goddess reportedly gave her refuge from their advances by turning her into a white opal. Opal’s translucent qualities, especially in the form of water or jelly opal, allegedly made it sought-after as a talisman of invisibility (and also was allegedly considered a stone of thieves and other criminals, as a result). The bright blue and green opals that some call “rainbow opals” are supposed to have been associated with the rainbow itself, and with its ancient Greek goddess, Iris. Some stories attribute fire opals to hardened bits of lightning (a bit like the Native Skystone), and black opals to the tears of an ancient god (evoking the image of the form of obsidian known here as Apache tears).
Whatever its symbolic referents (or lack thereof), opal in all its many forms remains a mysterious, mystical, magical stone. It may not be a true mineral, but its fiery, flashing beauty certainly qualifies it as both jewel and gem.
~ Aji
All content, including photos and text, are copyright Wings and Aji, 2015; all rights reserved. Nothing herein may used or reproduced in any form without the express written permission of the owner.
