HOW TO MEASURE THE RING CORRECTLY

Cut a strip of paper or use a non-slip ribbon. Wrap it around your ring finger, making sure it is neither too tight nor too loose. The ideal size for a ring is when it can be rotated without falling off your finger. Make a mark where the wrapped paper or ribbon meets the free end. Using a ruler, measure the length of the paper from the free end to the mark you made; this is your size.

OR

Use a ring that fits the finger you want to buy the new ring for, measure the inner diameter with a ruler, and use the table below to convert it to the European size.
Or print the  Ring Size Guide and place the ring over each of the circles below until the inner edge of the ring matches exactly with one of them. If the ring falls between two sizes, choose the intermediate size (mm).