As far as I know, THE place for carved stones is Idar-Oberstein in
Germany. The streets are lined with gemcutters and dealers. I’ve
bought stones in the past from A. Ruppenthal – it’s a large firm,
but they were very welcoming when we, literally, knocked on their
door one day.
They have a website (http://www.ruppenthal.de), but it’s only in
german. If you go to their site, select KONTACT, then EXPORT, and
you’ll find some phone numbers. I’m certain that they speak english.