new size chart

Tiffany (US) Size	Internal Diameter / Circumference (mm)
	15.7 / 49.3	J 1/2 k 1/2 L 1/2
	16.5 / 51.9	M L N
	17.3 / 54.4	O M O

Grab a tape measure, length of string or strip of paper.
Wrap it around the finger you’ll wear your ring on—if you’re creating a ring stack, consider where on your finger the ring will sit—and mark the place where it joins.
Lay your string or paper strip on a flat surface and use a ruler to measure the length up to the mark. Use the chart above to match the measurement to the closest Tiffany ring size.

Choose a ring that already fits your finger well.
Measure the interior diameter of the ring in millimeters (mm).
Use the measurement chart above to match the size of your ring to the closest Tiffany size in mm.