If you're considering buying an opal, you may be wondering: How can I tell if an opal is real?
With solid natural opals, doublets, triplets, synthetic opals and imitation stones all available, understanding exactly what you're purchasing is important.
Australia is famous around the world for its incredible natural opal, from Lightning Ridge black opal to Queensland boulder opal and the beautiful white and crystal opals found in Australia's opal fields.
Whether you're purchasing a loose opal or a finished piece of opal jewellery, here are some of the things to look for when choosing a natural opal.
What Is a Natural Opal?
Natural opal is opal that has formed through natural geological processes rather than being manufactured in a laboratory.
One of the things that makes natural opal so special is its play-of-colour — flashes and patterns of spectral colours that can appear to move and change as the stone or viewing angle changes.
Natural precious opal may display colours including:
red
orange
yellow
green
blue
violet
However, not every natural opal displays every colour, and no two natural opals are exactly alike.
An opal's colour, pattern, brightness, body tone and transparency all contribute to its individual appearance.
Are All Real Opals Solid Opals?
No — and this is where buying opal can become confusing.
The word "real" doesn't necessarily mean that an opal is a solid stone.
An opal doublet, for example, can contain a genuine slice of natural precious opal that has been bonded to a backing. A triplet can also contain a very thin layer of genuine opal.
The important question is therefore not simply whether an opal is "real", but what type of opal are you buying?
A reputable seller should clearly disclose whether an opal is:
Solid natural opal – naturally occurring opal without an artificially attached backing.
Opal doublet – a layer of precious opal bonded to a backing material.
Opal triplet – a thin layer of precious opal with a backing and clear protective top.
Synthetic opal – laboratory-created material designed to reproduce characteristics of natural opal.
Imitation opal – material made to look like opal but which does not have the same natural composition.
Knowing these differences allows you to compare opals more accurately.
How Can You Tell if an Opal Is Real?
There is no single at-home test that will reliably identify every opal.
Opals vary enormously, and some synthetic and imitation materials can look convincing. However, there are several characteristics that can help you understand what you're looking at.
1. Look Closely at the Pattern
Natural opals often have complex and irregular patterns.
Rather than simply looking for lots of colour, look at how the colour behaves when the stone moves.
Natural precious opal can display many different patterns and colour arrangements, and the appearance may change significantly depending on the viewing angle.
However, pattern alone should not be used to determine whether an opal is natural.
High-quality synthetic materials can also display impressive play-of-colour.
2. Look at the Side of the Opal
If you're trying to determine whether an opal is solid, a doublet or a triplet, examining the side of the stone can sometimes provide useful clues.
A doublet may show a visible boundary where the opal has been bonded to its backing.
A triplet may show multiple layers — the dark backing, thin opal layer and clear top.
A solid opal should not have an artificially attached backing.
There is one important exception to remember.
Boulder opal naturally occurs with ironstone attached.
The dark brown ironstone on the back of a boulder opal does not make it a doublet. The opal formed naturally within the ironstone rather than being glued to it later.
3. Don't Assume a Dark Back Means It's Fake
Seeing a dark or brown material behind an opal doesn't automatically mean that it is assembled.
This is particularly important when looking at Australian boulder opal.
Boulder opal forms naturally in ironstone, particularly in the opal fields of Queensland. Cutters often leave the ironstone attached because the precious opal occurs naturally in thin seams through the host rock.
This natural combination can create spectacular contrast between the dark earthy ironstone and brilliant opal colour.
4. Be Cautious of Opals That Look Extremely Uniform
Natural opal is famous for variation.
The pattern, colour distribution and brightness can change throughout a single stone.
Some manufactured opals may show highly regular or repeating patterns, although modern synthetic materials can be sophisticated enough that visual inspection alone isn't always conclusive.
This is why identifying an opal should involve more than simply deciding whether it "looks real".
5. Consider Where the Opal Came From
Origin can tell you more about the characteristics you might expect from an opal.
Australia has several internationally recognised opal-producing regions.
Lightning Ridge Opal
Lightning Ridge in New South Wales is particularly famous for black and dark opal.
Black opal has a darker body tone that can provide spectacular contrast against its play-of-colour.
Coober Pedy Opal
Coober Pedy in South Australia is one of Australia's best-known opal mining regions and is particularly associated with beautiful white and light opal.
Queensland Boulder Opal
Queensland is famous for boulder opal, where precious opal forms naturally within ironstone.
The natural ironstone is generally retained as part of the finished gemstone.
Understanding where an opal comes from can help you understand its characteristics — although origin alone doesn't prove authenticity.
Australian Opal vs Ethiopian Opal
Another common misconception is that Ethiopian opal isn't "real" opal.
Ethiopian opal can absolutely be natural opal.
The important difference is that much of the Ethiopian opal available today is hydrophane opal, meaning it is porous and can absorb water and other liquids.
This can temporarily change the stone's transparency and appearance.
Australian and Ethiopian opal therefore have different characteristics and care requirements, but both can be naturally occurring gemstones.
When purchasing an opal, the seller should accurately describe its origin and any relevant treatments or construction.
Why Are Some Australian Opals So Expensive?
Exceptional natural Australian opal is rare.
Mining does not guarantee precious opal will be found, and even when opal-bearing material is discovered, only some of it may have the colour, stability and quality required to produce a beautiful finished gemstone.
The cutter must then carefully assess the rough opal to determine how to reveal its best colour and pattern while preserving as much valuable material as possible.
Every finished natural opal represents a combination of geology, rarity and craftsmanship.
What Is Play-of-Colour in Opal?
Play-of-colour is one of the defining characteristics of precious opal.
As an opal moves under light, different colours can appear, disappear and move across the stone.
Some opals may predominantly display blues and greens, while others contain orange, yellow, violet and highly sought-after red.
The intensity of the colour is also important.
A bright opal that displays vivid colour across different lighting conditions can be particularly desirable.
Can You Get a Certificate of Authenticity for an Opal?
Documentation can provide buyers with useful information about the opal they're purchasing.
Depending on the seller and stone, this may include information such as whether the opal is natural, its type, origin where known, weight and other identifying characteristics.
However, a seller-issued Certificate of Authenticity should not automatically be confused with an independent gemmological laboratory report.
When buying an opal, look for sellers who clearly describe what they are selling and are willing to explain the characteristics of the stone.
Questions to Ask Before Buying an Opal
Before purchasing an opal, consider asking:
Is the opal natural or synthetic?
Is it a solid opal, doublet or triplet?
Where was the opal mined?
Has the opal received any treatments?
What is its carat weight?
Are photographs or videos taken of the actual stone I'm purchasing?
Does the opal come with information confirming its description?
A trustworthy seller should be happy to answer questions about the stone.
Buying Natural Australian Opal
One of the joys of buying natural opal is knowing that you're choosing something genuinely unique.
Unlike mass-produced jewellery where hundreds of pieces may look virtually identical, every natural opal has its own combination of colour, pattern and character.
At Cosgrove Opal, our passion is showcasing the natural beauty and individuality of opal.
Our opals are hand-cut, allowing each stone to be individually assessed and shaped to showcase its natural colour and character.
Whether you're searching for Australian black opal, boulder opal, crystal opal, white opal or another unique natural opal, understanding what you're buying is an important part of choosing a stone you'll treasure.
Learn More About Australian Opal
Want to learn more before choosing your opal?
Read our guide to the Different Types of Opal to discover the differences between solid opal, doublets, triplets, black opal, dark opal, crystal opal, white opal, boulder opal and Ethiopian opal.
You can also explore our Opal Care Guide to learn how to look after your opal jewellery and keep it looking beautiful for years to come.