corundum, inclusions.5, geology.11, Nigeria.12, gems

In April 2014, one of the authors (VP) was preparing a field expedition to visit sapphire deposits in Nigeria. During the preparations he contacted several West African gem merchants in Bangkok to arrange to see some samples and seek additional details about the sapphire deposits in Nigeria. This interest was fueled by the emergence of Nigeria as an important producer of gemstones over the past few years, and the lack of publications on the sapphires and sapphire deposits from and within the country. During one of these discussions he was shown a parcel of blue sapphires reportedly from a new deposit located on the Mambilla Plateau (Taraba State) in Nigeria (Figure 1). Over the following weeks, more parcels containing stones of similar appearance showed-up in Thailand, and also in Sri Lanka, as many Sri Lankan gem merchants reportedly rushed to Nigeria. All the people we met were very excited by the quality and the size of the stones being produced. Large clean stones were reported, some weighing between 100 and 300 carats with a nice blue color. Reports emerged that stones from the new deposit were being traded at very high prices. One stone reportedly sold for more than 1 million US dollars in Thailand. Photos of such stones rapidly started to appear on social media sites (Figure 2) and were also frequently encountered on the mobile phones of some West African gem merchants visiting Thailand.