Solid natural opal is rare and, in many cases, expensive. This has given rise to composites, imitations, synthetics and treatments to enhance the opal. In the case of Australian opal, which is non-absorbent and stable, we have also seen treated opal from other regions being passed off as Australian material. These distinctions are really important to know if you are buying opal as it informs the price.
Unfortunately, if you are not purchasing from a reputable and verifiable source, you may come across opal being misrepresented. It may be synthetic and tried to pass off as natural. Perhaps it has been smoked to mimic Australian black opal. It could also be a composite and mistaken for a solid. We’ll explain each of these misrepresentations in detail so you can spot the real from the fakes.
Doublets are a thin layer of precious opal bonded to a black backing. The backing could be black potch, ironstone, onyx or even black plastic. They are very popular in the market place as the result can be spectacular for a lot less zeros on the price tag in comparison to a solid opal. You can see more about doublets in this video with Justin.
Triplets are a thin layer of precious opal bonded between a black backing layer and a glass or quartz top. Similar to doublets but usually using a much thinner layer of opal, they have a domed quartz, glass or even plastic top on them. Again the results look amazing at sometimes a fraction of the doublet price.
Inlay is thin opal material that is bonded with a jewelry piece and inlaid into a cavity within the piece, for example a ring or bracelet. Inlay jewelry has been very popular in the past.
Whether the opal is loose or set into jewelry, there are a few ways to determine a composite from a solid;
- Look at the opal from the side. Does the line between the precious opal and the potch look uniform and perfectly level all the way around the stone (not to be confused with this as a natural occurrence which is rarely found all the way around an opal.)
- Look at the back of the setting. Does the back look to be opal or some other material? A natural sand inclusion or a change in potch colour may indicate a solid, whereas if the back is perfectly smooth and without blemish it may indicate a composite.
- Look at the opal face up. Can you see any lifting of the layers? Doublets and triplets do not like liquid and water as the glue can soften ans so you may see fluid incursion around the sides.
- A glassy like surface and a clear dome when viewed from the side is a clear indication of a triplet.
There are many natural minerals that can imitate opal including ammolite and labradorite. These are beautiful and can also exhibit the phenomena of play of colour which makes it confusing.
Many years ago we also saw plastic type imitations such as resin cabochons with aluminum foil embedded in them to create the play of color effect.
The most common ones today are rubber or soft resin type melding of colours which is then cut into shape.
Synthetics and Lab Created
Traditionally the main lab created opal was known as Gilson Opal. It had all the properties of opal but was created in a lab. These are no longer produced and most of this material is pretty rare to see.
The most common of the synthetic opals are the Kyocera opals. These are marketed under a number of names including Bello Opal and Aurora Opal. The material comes in a number of colors all mimicking the best opal you’ll see and is a mainstay of opal jewelry sold on marketplace sites such as Ebay and Etsy. Sometimes the small print will disclose its origin but most often it will not.
Andamooka produces a material which is classified as opal in host rock. When it comes out of the ground the color is fairly dull and the host rock is grey. Boiled in a mixture of sugar and hydrochloric acid, the material becomes blacker and therefore the opal far more intense in color. It was very popular as an ornamental gem in the 1970’s and 80’s. Most matrix you’ll see has been treated.
Opticon is a resin used to seal and harden. It is used to fill fractures and inclusions in opals, particularly volcanic and also some boulder material. In the case of boulder, it is always disclosed in our experience. It is not widely used but it’s always good to ask.
Smoked and Dyed Black Opal
In the past decade with the rise of vast quantities of Ethiopian opal, we have also seen merchants either smoke or dye these hydrophane opals to render them black – so mimicking the famed black opal of Australia. In most cases, these treatments are not disclosed and so it really is buyer beware.
Want to learn more?
Here are a number of videos we’ve made over the years on the subject of real vs fake. We have a whole lot more if you’re keen to dig deeper – simply search our Stories page for a list.
Justin takes you through some obvious and not so obvious differences between natural Australian black opal and treated black opal.
New synthetic opals are being created every year and manufacturers are getting better at replicating natural opal. Justin recently obtained some of the new material from Tony Smallwood.
The opal journey from mine to you
How can you be sure you have an Australian-mined opal? We discuss knowing where your opal comes from and the story of its unearthing.