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In October 2019, a concerned customer came to the Netherlands Gemmological Laboratory with several stones, each accompanied by a report from the Authentic Gem Security Laboratory. This name did not sound familiar, but according to the lab reports this organisation is based in Delhi, India. The customer asked us to check whether the issued reports were accurate. Testing of some initial samples reported as ‘natural star sapphire, heated, from Madagascar’, ‘natural sapphire, heated, from Sri Lanka’ (in pink, purple and blue) and ‘natural ruby, heated, from Mogok’ showed that they were synthetic corundum.
We also selected a ‘natural trapiche ruby from Mogok (Burma)’ and a ‘natural trapiche emerald from Colombia’ for further study. Both of them had translucent areas (pink to purplish red and bluish green, respectively) together with opaque dark grey ‘matrix’ material. The `ruby' specimen...