Our free Ring Size App is accurate and easy to use. Find out a ring size in UK, EU or USA measurements. All sizes F - Z included, from smallest to largest finger. Simply place your loved one's existing ring on your phone screen, and then adjust the circle until it fits the inside of the ring exactly. This app helps you keep an engagement ring or a special gift a surprise and saves you a trip to the jewellers. The Diamond Store – Luxury With Confidence