How To Identify Fake Opal


The popularity of Opals has exploded in the last few years. Buyers always need to be on the look out and do their best at knowing how to identify fake Opal.

Many shops across the world carry Opal and sell them to the general public at a price point that is lower than Australian Opals. Many buyers do not have experience with this type of Opal and many of them think they are being sold a synthetic or a fake Opal. We will try to explain the best ways on how to identify fake Opal below.

  1. Ethiopian Opals are mostly Hydrophane and do have a waxy different feel compared to other Opals. This can confuse new opal buyers. It is fine if the Opal feels like this.
  2. Look closely at the pattern in the Opal. Fake Opal or synthetics will usually be ‘too perfect’ and look man made. A natural opal will have less systematic patterns. They will also sometimes have a difference of colour or brightness across the Opal.
  3. Look for what gemologists call ‘Columnar’ structure or ‘snake skin’ pattern. Turn the Opal on it’s side and look for straight columns of color running vertically.This is the sign of a fake Opal.
  4. Look at the shape of the Opal, even a polished natural Opal will not be perfectly round or oval. Many times fake Opal will be perfectly round in shape.
  5. Always source your Opal from a reputable seller. We cannot stress this enough. A good seller will talk you through your potential purchase. Even if you are not happy with it they should always be willing to swap the Opal for a different one or discuss a refund.
  6. Try your best to educate yourself before you buy. The more you know what a real Opal looks like the easier it will be to buy a real one.
  7. If you can, ask the advice of a Gemologist to help you or find an Opal expert.

Below are examples of Natural Opals, note all the different patterns.

natural opals

Below is a sample of what fake Opal looks like.

fake opal

On Opal Auctions all of our sellers are verified and have knowledge about Opals.

Gilson Synthetic Opal

The most common form of synthetic Opal found on the market is the Gilson synthetic. This type of Opal has been around since 1974. It is created using Silica so it is a true synthetic version of natural Opal.

synthetic gilson opal

Chinese Synthetic Opal

This is the newest type of Synthetic to hit the market. It is made from a resin mixture so it is not a true Synthetic version of natural Opal. The pattern is very similar throughout the Opal. This is to be expected when something is manufactured. Natural Opal is unique and random while a manufactured product will be uniform.

Opal Auctions Rules

Vendors of Opals should follow these guidelines when trying to describe an Opal.

  1. If the Opal is smoked, it has to be declared as smoked and not as Black Opal
  2. Ethiopian Opal cannot be called Black Opal unless it is certified by an approved gem testing laboratory
  3. If the Opal is treated in oil it has to be disclosed as a treated Opal
  4. Dark base Ethiopian Opal is to be named as Dark Brown Opal
  5. If the Opal is treated with Opticon or any other method of treatment, it has to be disclosed as treated.

If you are interested in the patterns found in Opal from Ethiopia please read this informative article about patterns written by GIA.

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Hi James Rammon2013,
I agree with your view to a point, I have been cutting opal since the early 1960's and cut thousands of opal from around the world, including thousands of both Hydrpphane and non-hydrophane Ethiopian opal. This discussion, and varying viewpoints has been argued since the '60s and I have a strong belief that if it's black then it's a black opal, period!!
Until the recent (last 10 years or so) practice of taking Hydrophane opal and smoke treating it. It is so easy to achieve beautiful "black" Hydrophane opal that is very difficult to distinguish from natural black opal after the gem has been cut and polished. It isn't difficult to tell the difference between the two in the rough by an accomplished cutter, but proving it is natural, after the cut, gives the labs a reasonable doubt. If there's a doubt then i's not going to be certified black.
There are beautiful Black Opal from many places other than Australia, some of the best of those are mined in northern Nevada. I see where the rule on OA comes from that requires all other black opal from other locations to be called "Dark" or "Brown", but this brown designation came from the first Ethiopian opal find in the 1990's that was mostly brown based and a totally different composition than what is now being sold from Wello.
I think the "all other blacks be called brown" rule needs to be updated because there are many that don't have any brown characteristics! These need to be addressed with a current "Eye" since I don't see any change in getting clarity from the labs soon.
I have many writings and articles on opals and you can see my article on "Ethiopian Hydrophane" right here on Opalauctions.
Chuck Starbird, STARBIRDS

1st Dec 2017

My last purchase eBay was 3 years ago, I bought 4 natural Ethiopian black opals
One year later they went dull brown and the pattern disappeared, then year later were clear and then I threw them out
I know now they were treated smoked only and not natural
I paid $400 for them. That was my last purchases on eBay

31st Mar 2016

Hi James it is good question you ask
At present no approved Gem testing laboratory will issue report stating that wello opals are black opals.
There are so many smoked treated Ethiopian opals that are certified by secondary laboratories as black natural opals
For this reason we do not allow our sellers to use word black opals on Ethiopian opals but the word Dark.
You go to any other site besides Opalauctions and see smoked Ethiopians as natural black and even lot Indonesian opal as natural black opal
Until we are advised by approved laboratories like GIA,AGL,IGI our policy will stay the same
Scientists and laboratories are still investigating this and we are in contact with several, looking into Ethiopian and Indonesian opals in regards to treatments and what opal is natural or not
It is an exciting time as everyone wants to use word BLACK in describing their opals and we look forward to latest reports and will update on this site when more research is clarified
Regards wayne

30th Mar 2016

I like to point out that you allow Aussie opals to be called and listed as black such as this opal ,Auction #566653 ,but a Wello opal needs a gem lab report to be called black ? very bias in my opinion,if an opal is black its black and if its not its not,a name should not be used if the item description does not meet the color,do you really need a gem lab report to know if an opal is black or not? or do you think there are no black wello opals ? lol best regards

30th Mar 2016

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