Most tourists who visit Bangkok and want to buy Thai silk head to Jim Thompson. And there is no doubt that Jim Thompson offers high-quality Thai silk that caters to Westeners tastes.
But if you are looking for something more unique, or have a special request, there is another alternative: Almeta. You want 1-ply silk? Or 2-ply silk? Anything until 12-ply silk goes here. You want a certain weight? You request special colors? Different yarns? Pretty much any color can be matched.
Their silk gets produced in North-Eastern Thailand (Essarn), the traditional weaving place of Thailand.
The Almeta silk shop in Bangkok has been around since 1992 and has a solid and loyal customer base, especially among interior artists and designers.
If you just want a silk souvenir from Thailand, pretty much any place will do, but if you are looking for something special and unique, Almeta in Bangkok is probably your best address.
They also have homeware, accessories and lots of lifestyle products that can be seen in their showroom.