Solid, Doublet and Triplet Opals
Australian opals are the finest in the world. They have tremendous investment potential and are one of the few gemstones which have appreciated at a steady rate over the past 40 years. But before you race out and buy one, learn a little about them in what form they come and what is available. They fall into three categories:
Solid, Doublet and Triplets.
Solids are natural stones which have been cut and polished without being interfered with. Many have a natural potch or rock back.
Doublets are usually two pieces of opal cemented together. They are made by cementing a layer of high-grade opal to a black potch back, which enhances the colour. For economical reasons, many have thin faces. But domed cabochons made from good quality crystal opal, do in many cases, resemble fine quality black opal, which is due to the partial absorption of light by the black back. Their value is only a fraction of that of a solid black gem of the same quality. Although not always encouraged by the trade as an investment stone, the better pieces do bring a reasonable price and are certainly worthy of a place in any good gem collection.
Triplets are doublets usually made from a lower grade opal with clear domed caps cemented to their faces. The hardness of the cap may vary from glass to quartz, depending on the quality of the opal. The cap not only protects the opal but magnifies the intensity of the colour and pattern, greatly enhancing the overall appearance.