You can try to offer them on eBay. I would suggest you to sell the smallest pieces first just to test it and get some first references from customers.
Do you have only raw material for cutting or also some collection specimens?
Also try to find (via Google) someone living near to you, who sells such material. Maybe he is interested or he can give you some tips.
A good place to offer minerals (emeralds or others) to professionals and collectors are mineral shows.