Hi Lucy and All,
I think the first place you should go and have a look to is the
Jewelry Tarde Center's Silom Galleria, five minutes North from
Surasak BTS station. Althoug that part of Bangkok (Bang Rak) is
sprinkled with plenty of jewelry and gem related busineses, in that
particular building the concentration is huge. There are a a few
other buildings devoted to the trade, Gems Tower for instance, but
they don't compare to the JTC. In Charoen Krung Road (runs parallel
to the river in the BangRak area) and surroundings you'll also find a
lot of small -and not that small- mineral specimens, gems and siver
shops. If you finally go to Chanthaburi, you better go on the weekend
(Friday and Saturday), since in week days there isn't much movement
And a final pice of advice: if you happen to hit the streets in the
Songkran days (mid April I think), dress as casual as you can.
If I were still in Bkk we could have met, but I have just returned
to sad Spain.