Determining Your Ring Size
It is important to keep in mind that ring sizes can vary slightly from day to day or even from morning until evening due to such factors as temperature and humidity. One will often notice that a ring that is slightly loose during the winter months may actually feel quite snug in the summer. If you do not know your correct ring size the best way of assuring a proper fit is to have your ring size measured by a qualified professional.  If this is not possible you may estimate your ring size by following these instructions:

Ring Size Measured Size USA inches mm 4 1 13/16 46.5 4 ½ 1 7/8 47.8 5 1 15/16 49 5 ½ 2 50.3 6 2 1/16 51.5 6 ½ 2 1/8 52.8 7 2 3/16 54 7 ½ 2 ¼ 55.3 8 2 5/16 56.6 8 ½ 2 3/8 57.8 9 2 7/16 59.1 9 ½ 2 ½ 60.3 10 2 9/16 61.6 10 ½ 2 5/8 62.8 11 2 11/16 64.1 11 ½ 2 ¾ 65.3 12 2 13/16 66.6 12 ½ 2 7/8 67.9 13  2 15/16 69.1