FAQ : What is a doublet opal? What is a triplet opal? What is the difference between doublets, triplets, and solid opals? What happens when doublets or triplets get wet? Why do some opals go cloudy? How should I care for a doublet or triplet?
One of the most basic things you should familiarise yourself with when expanding your education on opal are those partially man made stones known as doublets and triplets. In summary, these stones are slices of opal glued to a black backing, designed to imitate the appearance of a solid black opal. Adhering the slice of opal to a black backing causes the colour to become much darker and more vibrant. However doublets and triplets are generally much cheaper than solid black opals as they only contain a small amount of genuine opal.
Doublets consist of two layers adhered together with glue:
A black backing which is made of either black industrial glass, black potch (colourless opal), hard plastic, brown ironstone or sometimes vitrolite.
- A thin slice of opal (normally crystal opal or white opal). The thickness of the opal in a doublet can vary, however it is generally thicker than the opal found in a triplet. The edges of the slice of opal are generally rounded off (if there is enough opal) to give the stone a cabochon (domed top).
Doublets can usually be identified by looking at the side of the opal – if the stone has been adhered together you will notice that the line where the coloured opal and the black backing meet is perfectly straight. This is necessary for the two layers to be adhered together. If a doublet is set into jewellery with the sides covered, it is extremely difficult, even for an expert, to tell whether it is a doublet or a solid opal. Since the top of the stone consists of pure opal, it therefore appears exactly like a black opal, and doublets thus have a much more natural appearance than triplets.
See below – examples of an opal doublet from several angles
Triplets consist of three layers:
A black backing as above
A paper-thin slice of opal in the middle
- A clear glass, quartz, or plastic capping in the shape of a dome. The slice of opal in a triplet is usually extremely thin (paper-thin) so the clear capping serves to give the stone a nice cabochon on top. The clear capping may also magnify the colour of the opal slightly, and also serve to protect the opal.
Because triplet opals have a clear non-opal capping on top, it is easy for an experienced person to identify a triplet immediately by the appearance of the stone. Triplets usually have a ‘glassy’ appearance and the light reflects differently from the top of the stone. You can look at the side of the stone to identify a straight line where all the layers meet, and also look at the back of the stone. If the back of the stone appears to be black plastic then you are not looking at a solid stone. Be aware however that it is also very common for a backing to be made of black potch (exactly the same stone which forms the backing of a natural black opal) or brown ironstone (which is also the natural backing for Queensland boulder opals).
Triplets are normally cheaper than doublets because they contain less real opal. Because the top of the stone can be made from synthetic material, triplets can be a lot more resistant to impact than solid or doublet opal stones. (Opal by its nature is a fragile gemstone).
See below – examples of an opal triplet from several angles.
Caring for doublets and triplets
Because opal doublets and triplets consist of layers which are glued together, prolonged exposure to water may cause lifting between the layers and infiltration of water. (This does not mean your opal will be ruined if you wear it in the shower once, or are caught in the rain.) If water penetration occurs, a doublet or triplet will take on a ‘foggy’ or grey appearance. You may even notice the appearance of condensation inside the stone. You should avoid getting a triplet or doublet opal wet to avoid water penetration.
Please note: There is a lot of confusion regarding the care of opals because of the different caring instructions for solid opals as opposed to doublets / triplets. Solid opals are fine in water – it’s only doublets and triplets which need to be kept out of water to avoid water penetration. Getting a solid opal wet will do no damage whatsoever.
Cleaning – Doublets & triplets may be wiped with a damp soft cloth and mild detergent, but should never be soaked or immersed. Avoid bleach, chemicals, cleaners, and ultrasonic cleaners.
Opal doublets and triplets can be a fantastic alternative to solid stones as they are much cheaper than solid black opals. Solid opals with the same appearance as an opal triplet can be ten times the price as they are rare and valuable, therefore they serve a useful purpose in making beautiful dark opals affordable. However, you need to be aware of what you are buying, and know how to correctly care for doublets and triplets to avoid water damage.