01Decisive
View it from the side and count the boundaries
One straight glue line means a doublet. Two, with a clear domed cap above, means a triplet. Continuous material front to back with colour extending into the depth means a solid.
Opal · Lovenhall Stone
How to Identify Opal Doublets & Triplets
Thin opal glued to a backing, with or without a clear cap. Legitimate, and a fraction of a solid stone.
Australia (Lightning Ridge, Coober Pedy), Ethiopia, Mexico, Brazil
Precious opal frequently occurs in seams a millimetre or two thick, far too thin to cut as a solid stone. Doublets and triplets exist to make that material usable: the opal slice is cemented to a dark backing — ironstone, potch, obsidian or black glass — which supplies the dark background that makes the colour play read strongly. A triplet adds a clear quartz or glass cap over the top, which magnifies the colour and protects the thin layer.
This is legitimate craft, and it has been standard for a century. The problem is that a triplet and a solid black opal can look extremely similar face-on, and differ in price by two orders of magnitude. So the construction must be established before the price is discussed.
The tell is always the side view. A doublet shows one straight glue line; a triplet shows two, and the cap's dome is a manufactured curve rather than a cut stone's. Both are also vulnerable in a way solids are not: water can penetrate the cement over time and lift or cloud the join, which is why doublets and triplets should never be soaked or ultrasonically cleaned.
Model-specific checks
What decides a Opal Doublets & Triplets
These apply to this model and not to the rest of Opal. Work them alongside the maker's general checks, not instead of them.
02Strong
Be suspicious of a deep bezel
A setting that wraps the girdle completely and hides the stone's profile prevents the only test that matters. It is not proof of anything, but on an expensive stone it is a reason to ask for the stone to be shown unset or certified.
03Strong
Look at the cap's curvature
A triplet's cap is a manufactured dome — geometrically regular, glass-clear, and often slightly too perfect. A solid opal's cabochon follows the rough and is rarely so exact.
The market
What a Opal Doublets & Triplets does on the secondary market
Doublets tens of dollars; triplets often single figures. A solid stone of the same face size can be a hundred times more.
An orientation for honest, unrestored condition — never an appraisal, and never a quotation.
Questions we are asked
- What is an opal doublet?
- A thin slice of precious opal cemented to a dark backing such as ironstone, potch or black glass, which supplies the dark background that makes the colour play read strongly. It is a legitimate way to use opal that occurs in seams too thin to cut solid, and it is worth a small fraction of a solid stone of the same face size.
- How can I tell a solid opal from a triplet?
- Look at the stone from the side. A triplet shows two glue lines and a clear, manufactured domed cap over a thin colour layer; a doublet shows one glue line; a solid opal shows continuous material front to back with the colour extending into the stone's depth. A bezel deep enough to hide the girdle should prompt you to ask for the stone unset.
All the Opal checks
Free tools of the room
Lovenhall StoneRead the stone itself
The tests tell you what it is. The instrument reads a photograph and offers a name to start from — then hands you back to the tile and the coin, which are what settle it.
Free on iPhone & iPad. An estimate, never an appraisal.
Or write to the house