Black opals are one of the rarest and alluring gemstones around the world. These precious stones show unique combination of colours when they are tilted slightly. Each time, colours and look is different from the previous position. This one of a kind feature of black stones makes it quite expensive. Most people believe that they cannot afford it because of its cost.
Partially man-made opals are known as doublets or triplets. A slice of opal is stuck to a black backing that looks similar to solid black opal; such stone is called a doublet. The dark backing makes the colours more dark and vibrant. Since the presence of the precious stones is very less, the cost of doublet opals is much less compared to a solid gem-stone.
Doublets can be identified by looking at the stone from its side. If the stone is attached to a black backing, then a fine straight line at the place of attachment can be observed. If the doublet is set into the jewellery, then it is very difficult to find the difference between a solid stone and a doublet.
A triplet has three layers, an extremely thin slice of opal, a black backing (like doublet) and a clear glass quartz or plastic in the shape of a dome. The presence of non-opal capping on the top, makes it easy for jewelers to identify them from solid opals. Like doublets, the presence of a straight line at the attachments site on the sides, confirms the stone is man-made. These stones are much cheaper than doublets and solid opals.
Doublets and triplets consist of layers that are adhered together with glue. Long exposure to water can separate the layers. The opal or the backing will not be affected, but they will be detached. Foggy or grey appearance in them, are signs of moisture in these stones.
Doublets and triplets should never be cleaned with water; they just have to be wiped with a damp soft cloth.
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