corundum, Madagascar.12, gems

High quality blue sapphires have been mined in Myanmar for centuries (Kane & Kammerling 1992, Themelis 2001, Hughes 1997). Until the end of the 20th Century, sapphires were mined from the Mogok Stone Tract, mainly in the western area near Kyatpin and around Mogok town. Towards the end of the 20th Century blue sapphire mining extended to the west around Kyauk Pya That, Kabaing and Kin, to the north around Barnard Myo and in the Chaung Gyi valley, and in the east around Peint Pyit village (Themelis 2008, Hughes 2016). Between 2011 and 2016 new production from Baw Mar area started to reach the market and attracted the attention of gemologists visiting the region (Phyo Kan Nyunt et al., 2013). GIA field gemologists visited Baw Mar operations in 2013, 2014, and 2015. It was evident the mine was not only the highest altitude mine in the whole of the Mogok area but also one of Mogok’s largest mining operations. Its sapphire production is interesting and challenging for gemologists as, its sapphire characteristics (chemistry and internal features) are slightly different from the classic Burmese sapphires. The aim of this research project is to expand our knowledge of these gemstones which can be a challenge in terms of origin determination. During the field expeditions and subsequent laboratory work it became clear that even within the same mine, sapphires can look different to one another depending on the area where they are mined; samples from the southern area are generally lighter in color than the sapphires recovered from the northern part of the mine. In this study, we analyzed samples collected at the office (located near the mining site where the production was sorted) during two separate expeditions. The samples were mined from opposite parts of the mine, southern and northern, respectively. The general gemological characteristics; inclusions, UV-VIS and IR spectra and trace element chemistry are covered. A description of the mine, mining techniques employed and preliminary geological observations are also provided. Most of the data collected reveals sufficient information to differentiate between the two sampled areas within the same mine. It is clear that the Baw Mar sapphires formed in a complex geological environment with the potential to produce a range of qualities (high to low), various inclusion scenes and variable trace element concentrations.