on the ring inside diameter in steps of . However in 1987 BSI updated the standard to the metric system so that one alphabetical size division equals 1.25 mm of circumferential length. For a baseline, ring size C has a circumference of 40 mm. India, Japan, China In India, Japan and China, ring sizes are specified using a numerical scale with whole sizes that does not have a linear correlation with diameter or circumference. Italy, Spain, Netherlands, Switzerland, Germany In Italy, Spain, Netherlands, and Switzerland, ring sizes are specified as the circumference minus 40 mm: for example, size 10 in this system is equivalent to ISO 8653:2016 size 50. Russia In Russia, ring sizes are equal to the inner diameter rounded to whole and half numbers, sometimes to quarters, for example diameter 16.92 mm is equal to size 17, 16.1 mm is equal to size 16. Equivalency table Resizing Most rings can be resized; the method of doing so depends on the complexity of the ring and its material. For example, rings of soft material may be opened using a special form of punch. In other cases, the ring may need to be cut open and material either added or removed before fusing the ring together again. All other factors being equal, sizing a ring up will cost more than sizing a ring down: while sizing up requires the jeweler add precious metal, sizing down allows them to remove and reuse it. Sizing beads Small metal beads called sizing beads can be added to the inner circumference of a ring to: Decrease the effective inner diameter of a ring that is too big, to aid in holding the ring in place against the finger Counterbalance top-heavy rings Keep a ring from spinning for wearers whose knuckles are much larger than their finger base Sizing beads are typically made of the same metal as the rest of the ring since it is easier to solder two similar metals. References Rings (jewellery) Sizes in clothing External links Ring Size