Using a ring you already own:

• Select a ring that properly fits the intended finger. Your ring should fit your finger comfortably, snug enough so that it will not fall off, but loose enough to slide over your knuckle.
• Measure the INSIDE diameter of the ring.
• Match the measurement of the INSIDE diameter to the ring sizes listed on the international ring size chart. For example : 14.9mm in diameter is a ring size H in Australia but would be size 4 in the U.S.
• If the ring falls between two sizes, we advise you to order the larger.

Tips for measuring your ring size:

Your finger size can change throughout the day, so it is a good idea to measure at the end of the day when your fingers are at their largest. Do not measure when your hands are cold; your fingers will be at least half a size smaller. Measure finger size 3 or 4 times to eliminate an erroneous reading.

If you are buying a gift, the best way - but not always the easiest way - is to borrow his or her ring (from the correct finger).