Hello , I am planning to visit Thailand on Tourist visa , that's what I can get , with a hope of selling some gemstones . I have gathered I need a work permit to sell my own duty paid stuff. There is info that says tourist visa holders can get temporary work permits but there has to be an employer to counter sign the application . In my case there will not be an employer so I need info on how do foreign gem dealers manage to operate in Bangkok/Chanthabury without being on wrong side of law which they say looks the other way for a while in case of self employed gemdealers but safer thing is to have the right documentation , that's the way I prefer.

I also need to know exact address of govt office that handles such visa requests on priority basis. Any and all info is welcome.

mrbgk

Any Thai consulate will accept your application for a visa.

It sounds like you need a business visa not a work permit. I've no idea how they work in Thailand, but that's what you'd need in most Western countries.