Question about morals...I was....?

surfing today at the beach and when I got back to my towel, I saw something shining in the sun. When I bent down to see what it was, I saw that it was a diamond ring--about 2 carats! Anyway, I took it with me and left! Do i turn it in to the police, put an ad in the paper, bring it to the lost and found at the beach, or consider it a found treasure? My husband told me we should have it appraised to make sure it's real and then sell it!! I feel bad doing that, but I have no idea how to find its rightful owner!