Proposing is one of the most exciting moments in life but also one of the most daunting! Once you have found a ring there are a few options if you don't know their ring size: - Wait until you've proposed and have the ring altered afterwards. That way you can get their finger measured accurately and get the sizing right first time. - Measure a ring they already wear. Usually there is a size or twos difference for the same finger on each hand so this isn't always the most accurate method.