Well first off don't expect to get anything close to what you paid for it, engagement rings have a huge markup as they prey on emotions and sentimentalty. All the places around will give you around the same price I found when I tried to sell my brothers ring for him a few years ago. So go to a few and see who gives you the best price. Iirc pawn shops were a bit higher than jewelry stores. If you want to get more of your money back sell it yourself on Craigslist or marketplace, do cash only and meetup at the police station to avoid scammers. But again don't expect to get anything near what you paid for it.