I've no idea since so far I've only done handmade stuff, there are probably a number of options you could try like going to a Jeweller that specialises in wax casting or something but the thing you have to bear in mind as well is that is the maths because even if it's casting you'll have to cover the cost of the materials on top of paying the Jeweller or Gold/Silver Smith for their time and then you'd have to make a profit yourself but I'd guess you'd already know that but I'd understand if you maybe want to do it as a promo item or something to reward customers with.
Ok, I am grateful for you trying to help and I mean no offense with this, but what is the point of replying with "I have no idea"?
I don't mean to be rude, but giving advice such as "you should ask somebody that knows about this" is not of much help since that is exactly what I am trying to do.
Have you heard of the gem vault here on Bitcointalk? The guy who runs that might be the one to talk to since he does quite a bit of casting, I've seen him showing his carvings, or if you want something more local you could just ask around the Jewellery shops and find out who supplies them.
Well, I opened this topic in the hope of getting insight from people that know about this stuff...?