As a preliminary study for a future field expedition to this location, researchers from GIA’s Thailand laboratory obtained a selection of 30 fine-quality rough sapphires from a trusted supplier in Bangkok. Representative samples were fabricated into precisely oriented wafers for the collection of high-quality optical data using FTIR and UV-Vis-NIR spectroscopy. Inclusions were identified using Raman spectroscopy, and trace-element chemical composition was analyzed using LA-ICP-MS.
A new report by the GIA laboratory in Bangkok, “Blue Sapphires from the Mambilla Plateau, Taraba State, Nigeria,” presents their initial findings. Although the inclusion suites, spectroscopic features, and LA-ICP-MS trace-element results appear similar to those of sapphires from other basalt-related deposits—including Cambodia, South Vietnam, and some Australian localities—the composition of minute “nano-inclusions” within some of the gems appears promising for origin determination purposes.