The following is to illustrate certain artifacts with opals and to provide some general and technical information about them. There are more varieties than you typically see in most retailers, and there are a lot of synthetics out there. There are also a lot of doublets and triplets on the market.

While either a synthetic, triplet or doublet might be attractive and affordable to many, they are not naturally. What’s worse is that most people don’t know the difference, and some entities will sell certain items without disclosing and explaining what these things mean. That’s the bad part. The other bad news is, if you want something natural, and good, anymore you’re going to pay for it if it’s of quality and pending the size and specifics.

Natural opals anymore have become quite expensive pending on the exact type. Yes, there is more than one type of opal. Pending what kind of opal it is, and it’s particulars, you will pay more or less for it. They were quite popular during the 1980’s as they have a myriad of colors which fit into the outrageous trends of the time. So suddenly they became popular, and they were relatively more affordable than they are now. The demand increased, the mines in Australia are simply not producing as much material. The strength in the Aussie dollar against the US dollar forced a doubling in the prices alone, so something had to give. That something was the quality and the rise of synthetics with the exception of certain higher end jewelers.

I’ve always been a fan of the more unusual stones, and things you don’t ordinarily see. The illustration below is a natural opal showing no evidence of enhancements that was purchased from AJS Gems. This is a 0.97 carat trillion cabochon magnified 45x.

This image was taken on a black background to give better contrast to the color, and to better protect the specimen when I studied it. It is considered a crystal opal as if you illuminated it from beneath, the light would shine through it, and it has a “crystal” clear body.

 The image may show a blue body as that’s how opals can appear on a black background. There are those opals that will naturally do that if they have a manganese backing that is where the base of the crystal is. Those are Boulder opals, and the manganese base is left beneath there on purpose to illustrate the fact that it is real.

 However, Boulder opals command a premium. So it’s cheaper to place a black piece of plastic or millstone beneath a white opal or so, and epoxy that to the base. Those are doublets, and they shouldn’t be as much. They face up in appearance as a Boulder opal would, but for considerably less. However, it’s a lesser quality opal that has been enhanced.

 The most common opals you see in the market place anymore are white opals. They have a white body. However, much of what you see naturally in retail today is considered to be a milk opal as it lacks the fire that an opal is supposed to have. The more fire, the more money these things command. The more flash, and the more red and rare colors in it, that can command a higher price also.

 White opals are amongst the least expensive of the opals. However, quality white opals are quite attractive. Consider the image below.

This is actually a white opal with a flat polished base. However, the absence of light gives the appearance of a blue-green body. This particular opal is from an older piece, and you can see an abundance of fire in it. Unlike the other specimen, you can’t see through it as clearly.

 This particular specimen was examined as the owner didn’t know if it was in fact a synthetic or not. There is a tell tale way to determine this by the patterns of the color. In either the case of the above or the first illustration, neither is a synthetic. Synthetics have a tell tale chicken wire or hex shape pattern to them whereas natural opals do not.

 Consider the following image:

 The following is a simulation through a computer generation of a pattern you might see in a given synthetic opal. This looks like patchy or impressionist type of image, and that’s what a synthetic opal will appear like under a standard jewelers microscope.

 You can see an example of an actual synthetic white opal here under a microscope. and you can see a chicken wire or lizard skin pattern here at 25x. It is possible to see hex shaped patterns with a standard 10x loupe. You might be able to being to see traces of these things to the unaided eye also if your vision is sharp enough and the specimen shows it.

 If you observe the image from the link, you can see the hexagonal shaped pattern. Some refer to it as a lizard skin pattern or chicken wire effect. This is vastly different than the above images. Note that how the body of a white opal under a microscope will turn black as it is unable to reflect light back.

 The following is an example of a white opal as shown under a higher magnification.

 There are a few things worth noting in this particular specimen.

 If you notice, there are areas that are curtain like. These are actual silicate spheres that form a curtain shape or an aurora type pattern. This is not the same as the layered pattern.

1. The body appears black although this is a white opal. Opaque material will do that.
2. Note the presence of the yellow hues in this specimen. With the exception of some synthetics, yellow only occurs naturally in Australian opals. I have yet to see any Ethiopian opal that has yellow in it. However, the absence of yellow alone should not be an indicator as to origin.
3. You can see some faint evidence of oiling of this particular specimen.

 The oiling of opals is a common enhancement, and it is done to preserve certain fractures and cavities from growing. Opals can be quite sensitive to the absence of moisture. It is not a significant enhancement, nor is it something that you can see with the naked eye.

 This is an alternate view of the previous illustration. There are certain artifacts highlighted in white and numbered accordingly.

 If you notice towards the right and center, there is what appears to be a branching of yellow. This is a common thing with natural opals. These are actually groups of silicate spheres that form these structures.

1. If you notices a slight brownish streak, this is the presence of oil within the crystal.
2. Notice how there is almost a gradient pattern of green needle like stacks of spheres? This is common to see these sorts of things in natural opals. These are groups of tube like structures that are stacks of silicate spheres. Pending the diameter of the sphere, that determines the color of the flash.
3. This is another example of that curtain effect of tubes. These happen to be red, which is a rarer color. Also note that the directions are more random in 3 space with respect to each other. This is the case with natural opals. You may see many like artifacts that look as if they were randomly placed like that.

 This is the same specimen near 90x or so. Not the tube like structures with the reds? There are also some violet-blue areas which are also considered to be rare. There is a distinct absence of hexagonal shapes or the chicken wire effect.

 This is a highly magnified illustration of a portion of the same crystal opal as featured at the beginning of this text. This is the same specimen from AJS Gems. Not that there is a clear to violet color body vs. black. That’s how a crystal opal appears under the microscope. One can also observe some like tube structures with stacks of silicate spheres. This one is of particular interest as we can see a rainbow type gradient which you normally don’t see.

 Now, there are those dealers who either don’t check what they sell, or they have no clue as to what it is they’re selling. The issue is there are those places that sell certain opals as being just that-and they turn out to be not purely opal.

 There was a specimen in which I came across in which someone bought. They wanted my opinion. The first thing I noticed were 2 things. It had a harlequin type pattern about it, and it had a beige tone. It wasn’t a crystal opal in appearance. It wasn’t a white body. It wasn’t black by any means. It was in a pendant and disclosed as being a 9.00 carat opal. Given the flash in it and such, the price wasn’t bad.

I began to examine this pendant, and I quickly realized that there was something that looked like glue behind the piece as the light shined through it. I immediately started to become suspicious that something was wrong.

From this vantage point, it looks like a harlequin type pattern but with a rather interesting polish. From just this picture, one might say crystal opal.

A little further examination discovered that there appeared to be some sort of bubble type inclusion near the lower left. That’s not something you see with a natural opal.

So obviously some additional examination was needed, and I took a look at the side from various magnifications.

You can clearly see the opal on top, and above the frame but beneath the opal, there is something white. The body of the bottom layer doesn’t match the top. You can see a defined line. There is also the absence of any flash suddenly, and this went around the entire piece. So my first thought was it was a doublet. It had to be.

This is an alternate view of the piece from the side. You can tell there is a layer of a very thin piece of crystal opal, and there is a piece of plastic material beneath it. You can see the line. Notice how the flash is less quadrilateral in shape? This particular piece is a slice of a crystal opal and was cut more or less parallel to the c-axis to give it a harlequin type pattern. Most of this piece is not even opal but more man made material.

This is another view, and this was to prove to the vendor that this seam was all the way around. It also occurred after viewing this picture that perhaps this wasn’t a doublet but a triplet. You can see the bottom layer with a closely matched color from fabrication, and the thin slice of crystal opal on top. If you look closely, there is what appears to be a third layer on top of that.

This particular specimen was never immersed in oil, but that would have proven immediately if it was in fact a doublet or triplet. It appeared that there was a thin layer of plastic over the entire top to protect the center layer. This was around 40 magnifications.

This was the back side of the piece between 40 and 50 magnifications. It’s totally opaque. More importantly, you can see the cross hatch pattern from the machining that was done as part of the fabrication process.

So in a case like this, the item was sold as a 9 carat opal. 9 carats is the weight of the thin sliver of crystal opal that would be otherwise unwearable, the underlayment, and the top covering as well as the epoxy to hold it all together.

The price for a quality 9 carat white or crystal opal can retail in the US for several thousand dollars. If it’s a crystal opal, it will command more, and a black even more than that. However, this was what appears to be a triplet and never disclosed. So for what was being asked and presented as a major discount was not really a deal as the piece could not have possibly listed for higher than what it was.

Natural opals such as boulder opals do have a backing on them that’s a chocolate type color with a grain. Lapidaries and high end dealers will leave that backing there to illustrate it is in fact a natural opal. A doublet or triplet will have either a piece of black millstone or plastic attached with epoxy to the base. As such, while these things can be more durable than their natural counterparts, they should be considerably less money.

If you buy an opal, and you don’t see a backing to it, that doesn’t mean it’s been enhanced. There are many crystal and white opals (as well as black opals) that have no backing. If such is the case, the base of the stone should match that of the rest of the stone. If you see a blue-green body, look at the underneath. If you see a solid black color, it’s a doublet if not a triplet. If you see something like a chocolate rock with a grain going through it, you know it’s natural.

In general, there are 2 things to consider with opals-body color and the amount of flash.

White Opals These are perhaps the most common. If they have little flash in them, they shouldn’t be as expensive. The more flash they have, the more money they are. A white opal in a larger size loaded with color (especially reds, pinks and oranges) will command a premium price. Pending the price guide you look at and the size, larger sizes can be a few thousand dollars per carat. On the other end of the spectrum “milk” opals may be well under $100 a carat pending the size.

Jelly OpalsThese are sometimes in line with white opals or slightly less pending on the retail price guide you look at. It is like a white opal but instead of flashes of color, it has more of an effect of several zones of color like neon tubes or a plasma effect. If you could imagine a piece of multicolored silicate gel that shifts every color of the rainbow within it, that’s what a jelly opal is. The phenomena is more like a color shift property across the spectrum where the colors blend than it is patches of flash like other opals. If you like something that has an antique motif to it, you might like these as they have that effect to them.

Boulder Opals These come from a certain mine in Australia, and they typically have a greenish blue body. In the wholesale markets, they can be less money. In retail, they aren’t so cheap. They can command more than a white opal. If it has a lot of violet flash in it along with some yellow and red, those can fetch premium prices. Look at the backing underneath to make sure it’s not a doublet. Most of what is in retail jewelry stores now days that appears to be a Boulder opal is in fact a doublet. If you visit a high end retailer, that’s another story. The more variety of color within the specimen, the more desirable the piece. Smaller sizes are more common than larger ones. It’s more difficult to find a specimen with more flash and more of a variety of color in it. You will pay more for that. Some collectors love these things, and they make some beautiful pieces of jewelry when set in something like a bracelet or pendant. They also make great cuff-links for men and tie-tacks if you wear those.

Crystal OpalsMost of what I have seen in the retail market places, these are very uncommon. The price guides have these listed for premium prices. When I say premium, a 1 carat stone of very good quality can go for around $1000/carat. If you want to double the size, triple the price for comparable quality at a retail level. You might find smaller accent sized stones in your better department stores if you’re lucky or a higher end jeweler. You may see these in estate pieces such as bracelets. They have a transparent to translucent clear body. Typically you see a lot of flashes of blue and green in them. Certain specimens may have a little bit of a jelly undertone to them here and there, but they are still considered to be crystal opals. The more flash, the more color, the better the quality. The best ones come from Mintabie, Australia and from Ethiopia. However, the ones from Mintabie are said to be not quite as sensitive to heat in comparison to others. However, treat them with the same care as you would any other opal. These are highly sought after by collectors.

Semi-black OpalsThere are many a dealer who will call a semi-black a black opal when technically it’s not correct. However, it is somewhat a generally accepted practice to call a semi-black a black. In the price guides, some will put them on par with crystal opals. Others will put them a little bit higher in price. So what’s the difference? It’s basically a crystal opal with more tone. When you see a translucent smokey grey body in the piece, that’s a semi-black. Technically, if a crystal opal has a tone on the GIA scale between 4 and 6, it is considered to be a semi-black. Those are rare and often put in the same category and class as the famed black opals. You might have an easier time finding a semi-black opal with a lot of color and fire in it in comparison to it’s black counterpart.

Black OpalsWhen an opal has a body that appears to be black, then it’s considered a true black opal. Technically, the tone of the body has to be between 7 and 10 on the GIA tone scale. These are the most expensive of all the opals, and the rarest. Much of what you see may have a moderate amount of fire in it, and even still they start at something like $1500 a carat for OK goods. That’s at a retail level, and we’re not talking about anything of a great size. The most sought after, rare and exotic are the ones where they have more flash than they do body, they’re pitch black in the body, and they have about every last color under the rainbow. When I say that, I mean everything from violet, loads of yellows, greens, pinks, oranges, and red. Larger sizes are quite expensive. If you find something like that at a retail level (barring an estate piece), a 5 carat specimen of that quality will wholesale between $10,000 and $15,000 per carat. If you want a good 5 carat black opal or better, and you go to a retail jeweler, it’s going to be in one of those places, and be prepared to pay 6 digits for it. Museum quality goods are extremely rare, and pending the size and color, they can appraise for well over $20,000 per carat.

Mexican Fire Opals These generally can be described as a jelly opal or in some cases like a regular opal with one difference. It has a transparent or translucent orange body. If you can picture the color of a really good mandarin garnet, or orange jam, that’s what the body is of the color. Prices can very from very inexpensive to expensive pending on the amount of flash. They are available in more appreciable sizes, but not necessarily with as much fire to them as other species. However, when they have the fire in them, they can bring premium prices as those are not so common.

Pink Mexican Opals These are mined out. If you see a true pink opal, it’s a true collectors item. You’ll only find them in an estate piece. They’re like a white opal and they have a more or less opaque body to them, but they have the flash and fire of other opals. They are very rare. They were once popular circa 1950’s or thereabouts. There are no more coming out of the ground. They haven’t been around for many years, but they are a truly unique specimen. If you happen to find one of quality, and it’s within budget, it’s a true collectors stone that few can truly appreciate.

-joe