I went to the gem and jewelry show in BKK a couple years ago and most of the rough being offered was by Africans. There were a lot of Indians and some Thais selling cut stones and a few Russians selling synthetic rough. The Chinese were welling cut synthetic and jewelry. I enjoyed the show but doubt if I would make much effort to go back even if in Bangkok. I didn’t see so very much of interest that I couldn’t find at home(US) at about the same price.