Thailand.12, Bo Ploi, blue sapphire, inclusions.5, corundum, gems

Gunawardene and Chawla describe the sapphire deposits of Bo Phloi, Kanchanaburi Province, western Thailand, a locality that had become an important source of commercial blue sapphire during the preceding decade. The paper gives details of the locality and its accessibility and reviews geological investigations of Kanchanaburi, comparing the occurrence with the better-known basalt-associated gemfields of Chanthaburi–Trat in eastern Thailand. The authors present chemical and physical data for the sapphires and grade their colours using the DIN colour system. Particular attention is given to microscopic examination: characteristic internal features are illustrated with photomicrographs and analyzed for their value in characterizing Kanchanaburi material. The study provides an early detailed gemmological description of sapphires from this important Thai basalt-related deposit.