How do I know my partner’s ring size?

How do I know my partner’s ring size?

Use a pen and paper (or your finger) to document their ring size. You can trace the inside of their ring on a piece of paper and then your jeweler can figure out the diameter of the ring from your sketch (Blue Nile also has a printable ring size guide if you're planning to buy online)!

How do I find out my girlfriend’s ring size without asking?

Perhaps the easiest way to get her ring size without her knowing is to use a ring she already owns. Wait until your girlfriend is not around and check her jewelry box for a ring you've seen her wear on the ring finger of her left hand. Take the ring to a jeweler and get her size.