How to tell if an Opal is real
FAQ : How can I tell if an opal is real? What is Gilson opal? What are synthetic opals? How can I tell if an opal is synthetic? What is synthetic opal? How can I identify opals? Is my opal real?
Synthetic Opal, Doublets & Triplets
Synthetic (Gilson) Opal
Ever wondered if you're getting what you paid for? Synthetic opal does exist, as well as partially man-made stones such as triplets and doublets. In this article, we give you the low-down on how to know exactly what you're buying. (See our article on types of opal for a more detailed explanation of the difference between solids, doublets, & triplets.)
Does the stone have a white body tone, or is it transparent? If so, it's almost certainly a genuine solid, and you're looking at a white or crystal opal. All doublets and triplets are dark in body tone because they have a black artificial backing.
Look at the side of the opal - if it has distinct visible 'layers', it may be a doublet or triplet (i.e. not a solid opal) In this case, one of the layers will be a thin slice of opal, attached to the dark backing. A triplet will have a third layer, which is a clear, domed layer on top of the opal.
Look at the back of the opal - does it look or feel like a kind of hard black or grey plastic? Triplets are often glued on to a black plastic, glass, or vitrolite backing. Doublets are a little more difficult to identify, as they often use a natural potch (black, colourless opal) or ironstone (the brown boulder opal host rock) backing. In this case, look at the side of the stone again and see if the 'join' between the opal and the backing is perfectly flat (i.e. the line around the circumference is perfectly straight). Most genuine solid opals have an irregularity in this area - curved or bumpy due to their natural formation - whereas a man-made stone will be perfectly flat because the two sections are flattened so they can be glued together. Be especially wary if the opal is set in jewellery and you cannot see its back or side. Even an expert will have difficult identifying a doublet set once it's set in jewellery with the back & sides covered.
Does the top of the opal look 'glassy'? Triplets are capped with hard clear plastic or quartz, so the top of the opal reflects differently to that of natural opal. Also, if you can see through the top of the opal from a side view, you are probably looking at a triplet.
Be educated before you buy. Know what real opal looks like, and compare what you have seen to what you are buying. People have been known to set coloured tinsel or foil underneath clear plastic to make an 'imitation opal'.
Synthetic solid opal can be very difficult to identify, unless you are an expert, or have a lot of experience. Look closely at the pattern - Opal created in a laboratory (Gilson opal), displays bright colours in large patches of colour. The pattern is often 'too perfect' and ordered, and can also often display a 'snakeskin' pattern. If you are still not sure, take it to a gemmologist or an opal expert.
Lifting - If your opal becomes 'cloudy' after a while, you are probably looking at a triplet or doublet. This cloudiness happens when a triplet or doublet has been worn in water over a long period of time, causing the glue between the layers to deteriorate and allow water penetration.
Please note, triplets, doublets, or synthetic opals can be a great affordable substitute for natural opal. However, you should always be aware of what you are purchasing, to avoid being overcharged or misled.
In Summary: Always try to buy from somebody who has gemmological qualifications and offers a 'certificate of authenticity' with their opals. Reputable dealers are accountable to their gemmological associations and may also be members of a jeweller's or opal association.