Where can I sell my 2ct diamond?

A two carat diamond is a significant investment.

You are well advised to pay for a certified gemologist to survey the stone, so that you have a certificate describing it.

Then, you can shop around and gather prices for such a stone. This will give you a good idea for the price range you can ask.

Then, you can advertise, put it in a consignment shop, deal with a pawn broker, or conduct a private sale by Word-of-mouth.