American ring buyers might be shocked that British rings don't have the same ring sizing standards. Instead of using numbers to identify ring sizes, the British use letters, ranging from G to Z. To get the right fit, Americans can convert their ring size by measuring their finger diameter in millimetres, using Blue Nile's conversion chart to identify their true British ring size.
Wrap a strip of paper around your finger, below the knuckle. Mark the area where the paper overlaps. Lay the paper on a flat surface.
Using a ruler with millimetre measurements, measure the length from the edge of the paper to the mark. If the total measurement falls between two millimetres, such as 45 and 46, do not round up.
Go to Blue Nile's ring size chart (in Resources), and match the millimetres on the "Measured Size" column. If the ring measurement does not exactly match what is listed, choose the next-highest measured size listed on the chart. Look to the left of the "Measured Size" number to find your ring size.
Measure when your finger is warm, not cold; cold shrinks the finger's size.