Gemstone Doublets
Sapphire Doublet |
Recently a prospective customer wrote to us to ask about a sapphire doublet he had just acquired. He wasn't quite sure what a doublet is and wondered whether the gem was especially valuable.
On the face of it, a doublet sounds like a good thing; you would think it should be twice as good as a singlet. But unfortunately that's not the case in the gemstone world.
A doublet is a stone composed of valuable gemstone material in combination with other, less expensive, material. This is not a natural occurrence, but rather a man-made fabrication where two pieces of material are glued together to form a sort a composite or "gemstone sandwich." Usually the crown or top of the stone is natural gemstone material while the bottom or pavilion is composed of an inexpensive material such as synthetic sapphire or quartz or glass.
There are several reasons why a gemstone doublet may be created. It could be done with the intention to deceive, since well-fabricated doublets can only be detected by the expert eye. Because a 2 carat sapphire doublet may contain less than 1 carat of natural sapphire, it would certainly be fraudulent to sell a doublet as a fully natural sapphire.
Opal Doublet |
A sapphire doublet may also be produced simply with the intention of saving cost. As long as the stone is disclosed as a doublet at the time of sale, there is nothing wrong with this. However, an ethical dealer should ensure that his customer knows what he's buying when he purchases a doublet. That was clearly not the case with the buyer who wrote to us asking about the value of his sapphire doublet.
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In the gemstone market, any kind of gem may be produced as a doublet, especially expensive varieties such as sapphire, ruby and alexandrite. But you will most often find doublets in opal, since high quality precious opal is both very expensive and fragile. An opal doublet consists of a slice of precious opal usually glued to a black backing (common opal or glass), designed to imitate the appearance of a solid black opal. Adhering the slice of opal to a black backing causes the color to become much darker and more vibrant. Opal doublets are well regarded as a less expensive alternative to solid opals which are very expensive in larger sizes. |
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