The jewellery company Tiffany & Co sells a wide variety of rings including engagement, wedding and casual rings. If another person purchased a ring as a gift for you, there is a chance that the ring will not fit your finger properly. Like many jewellers, your nearest branch of Tiffany & Co may resize the ring for free. If Tiffany & Co will not resize your ring, or you don't have the receipt, you can take the ring to a jeweller along with a size chart.
Visit the Tiffany shop where your ring was bought. There are several branches in and around London and one in Manchester. In many cases, the shop will measure your finger and resize your ring for free. If they won't resize the ring, you will have to take it to an independent jeweller.
Measure your ring finger using a tape measure. Determine the circumference of your finger in millimetres. Measure in the evening, when your finger is widest, on a day when you are not particularly bloated or dehydrated.
Print out a ring size chart (see Resources).
Using the tape measure, determine your ring size using the size chart. UK ring sizes range from A (37.8 mm) to Z (68.5 mm).
Take your ring and the size chart to a jeweller and tell him you want to resize the ring. Explain the current and desired size of the ring. In many cases, a jeweller will remeasure your finger and ring to double-check the size.
Ring sizes change when you lose or gain a large amount of weight.