Gemstone question

[Paramedic]

I'm hoping someone will be able to give me some advise on a strange situation I have found myself in. This is not Rolex related, but here goes. My question is, how would someone go about selling some rather large gemstones? Emeralds, opals, etc we are talking 35-50 carat each. These are cut, just not mounted, all are very real. I just have no idea where to even start with pieces this size. I stopped at a few local jewelers, after they picked their chins up off the counter they really did not have any good ideas. Any advise would be helpful.

Thanks Everyone