If I sold it at a pawn shop or jewelry store?

Answer:
It depends on the quality of the diamond. Usually if you go to a pawn shop, they won't give you anything near what you purchased it for. The problem is, most jewelry stores mark up prices on everything so drastically, that the true value of a diamond is lost. Pawn shops won't give you a tenth of what you paid, because they still have to sell it.

You're better off putting it in the paper or eBay. That way you won't lose so much in the turn around.

Answer:
probly not $4,000