How much do 1ct diamond cost?

On the Fancy Diamonds site, we found a .81 carat natural Fancy Green diamond with a VS1 clarity listed for about US$45,000.

If you have a green diamond to sell, best practices dictate that you pay for a certificate from the GIA organization, to verify that your diamond is a natural green stone. The certificate, as well, will verify the carat weight, the cut and the clarity of the stone. With these details, you can value your stone.