u/Ghost03272

Ok so kinda freaking out here. I'm proposing and I finally got my ring. My problem is it's the wrong size.

She swears up and down no matter what that she is a size nine but no matter how many rings I got her as presents they don't fit and I get tell her she's not since that be a dead giveaway. I want to take it to a jeweler but I don't know what size to tell him. She's asleep and this was one of the rare times she's fallen asleep without the ring. I remember hearing something about if you take both objects and a quarter, you can measure the exact width of what it is but frankly, no idea how to do that. Can anybody help me out?