Where to buy a Diamond Ring in Bangkok?

I have been to Bangkok many times and I can recommend THANA GEMS -Pathumwan Jewellery.lst MBK Center,Telephone(02) 686-3506 Mobile (01) 827-2249. It is on the ground floor linked up to the Pathumwan Princess Hotel. The owner is a very nice man and will do any alterations for you if your ring needs sizing.