corundum, assembled stones.8, treatments.6, gems

When a jeweler damaged a customer's ruby recently, he agreed to replace the stone. However, when the replacement stone was submitted for appraisal, the appraiser suspected that the stone might be a doublet. Examination in the New York lab proved that although the stone is a doublet, it is no ordinary doublet: it consists of a natural ruby crown and a natural ruby pavilion. In Gems, Their Sources, Descriptions and Identification, Webster referred to these stones as true doublets." Shipley called them "genuine doublets." Although they are very rarely seen in the labs, one Far Eastern gem dealer informed us that these stones have been seen in Thailand. Fine rubies over one carat are rare. If the potential fraud went undetected, a true doublet weighing one carat could be sold for much more than the value of two half-carat stones. A bezel setting could malze the separation plane very difficult to detect."