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New Nigerian Source of Blue Sapphire


 The Mambilla area of Nigeria has been producing beautiful Sapphire for many years.GIA has been able to conduct analysis on samples from the are.
The recent arrival of high-quality blue sapphire from a new source  in Africa has caused considerable excitement in the Bangkok marketplace. These gems, reportedly from the Mambilla Plateau in Nigeria’s Taraba State, are available in large rough sizes, some as big as 100–300 ct. Like previously documented Nigerian material, these sapphires are mined from basalt-related secondary deposits. Yet the quality is significantly better than any seen to date from those sources. Initial indications suggest that this new deposit might provide a winning combination of size, high clarity, attractive color, and good crystal habit from a cutter’s perspective. Indeed, one especially fine stone is rumored to have sold for in excess of US$1 million.

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.

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