gems, corundum, treatments.6, ruby, sapphire, beryllium, Be diffusion

More than a decade has passed since Be-diffused corundum was first recognized by gemologists, and such material is still present in the gem market. This study summarizes data from about 22,000 pieces of corundum submitted for identification to the Central Gem Laboratory in Japan in 2012. LA-ICP-MS analysis revealed an average of 10 ppm beryllium in Be-treated samples, regardless of corundum colour or the specific spot analysed on a stone. Traces of naturally occurring Be also were detected in corundum that was identified in the laboratory as being heat treated without Be-diffusiontreatment. Such stones were identified by their colour distribution and by wide variations in Be measured in different spots, which was positively correlated with other trace elements (i.e. Nb and Ta in blue sapphires, and Zr and Hf in yellow to yellowish orange sapphires). These elements were typically associated with clouds of minute inclusions, but they also were present in the blue sapphires in areas where no inclusions were visible with the gemmological microscope. While the LA-ICP-MS technique is useful for identifying Be-diffused corundum, the simple presence of Be is not always proof of this treatment.