Is there any website I can find the price per cwt. for gemstones?

I am getting in to a new hobby of gemstone hunting,buying,selling, ect. I am kind of scared when it comes to buying because I am not sure if I am getting a good deal and can sell them at a good price for profit? Example I have a little over 50 diamond cut Brazilian emeralds at a total weight of 10 cwt. I have been told that I got a good deal on them but I don't know what they are worth per cwt. to sell them. Is there a website or something I can look up to get this information?