I just bought my husband a new wedding band for Christmas, and what I did was paid attention to when he took the ring off. I realized that he always took it off when he put on lotion. One morning I went in while he was putting lotion on and struck up a conversation with him. While I was talking, I just pretended I was playing around with his ring, put it on my pinky and spun it around, etc. Before I set it back down, I put it on my thumb and paid attention to how it caught on my knuckle. From there, I just went in and asked to see their ring size samples, and picked it out. I'm happy to say that I've checked, and it ended up being the exact same size as his old band! And he has no clue!!!