He takes it to the jewelry store that will pay him the most, and it will be a LOT less than $59k. Something is only worth what somebody is willing to pay for it. He can sit there all day and say it's worth $59k, but if no one wants to give him that much, it's not worth that much. Is it?
Or he can take his chances on his own, trying eBay. He can set his own price and take offers, and if he gets $59k, it will cost him about $7,700 in fees.