Ring size

Ring size is a measurement used to denote the circumference (or sometimes the diameter) of jewellery rings and smart rings.

om plastic, delrin, wood, aluminium, or of multiple materials. Digital ring sticks can be used for highly accurate measurements.

Measurement systems

International standard

ISO 8653:2016 defines standard ring sizes in terms of the inner circumference of the ring measured in millimetres.[1] ISO sizes are used in Austria, France, Germany, Belgium, Netherlands, Scandinavia (Norway, Sweden, Denmark, Finland, Iceland), and other countries in Continental Europe.[citation needed]

This international standard specifies a method to measure the ring-size using a ring stick (also called a mandrel or triblet) with defined characteristics, which is used during manufacturing steps, and specifies the designation of the ring-size.

For jeweller-consumer relationships, the finger size is measured with a finger gauge set made up of a ring for each size with the same diameter and tolerance as the ring stick ones. The sizes are in millimeters and correspond directly to the outer circumference of the ring stick to the inner circumference of the finger gauge.

 ISO size (internal ring circumference, mm) Internal diameter (mm) 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 15.6 15.9 16.2 16.6 16.9 17.2 17.5 17.8 18.1 18.5 18.8 19.1 19.4 19.7 20.1 20.4 20.7 21 21.3 21.6 22 22.3 22.6 22.9

Other ring size measurement systems are used in areas that do not use ISO 8653:2016.

North America

In the United States, Canada, and Mexico, ring sizes are specified using a numerical scale with 14 steps, where whole sizes differ by 0.032 inches (0.81 mm) of internal diameter, equivalent to 0.1005 inches (2.55 mm) of internal circumference. The relationship of this size (${\displaystyle s_{NA}}$ ) to ISO 8653:2016 circumference (${\displaystyle C_{ISO}}$ ) is ${\displaystyle C_{ISO}=2.55\times s_{NA}+36.5}$ , while the relationship to ISO 8653:2016 diameter (${\displaystyle d_{ISO}}$ ) is ${\displaystyle d_{ISO}=0.8128\times s_{NA}+11.63}$ .

The Circular of the Bureau of Standards[2] summarizes the situation with this system: "While there apparently is only one standard in use in the United States, in reality, because of the lack of specific dimensions and because of the errors introduced by the adoption of a common commercial article as a pattern, there are many, although similar, standards." The standards are generally consistent and remain so. There does not appear to have been any improvement in the standard since then.

Ireland, United Kingdom, Australia

In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale with half sizes. Originally in 1945, the divisions were based on the ring inside diameter in steps of 164 inch (0.40 mm).[3] 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.[4]

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, 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.[5]

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

Ring dimensions in various ring size measurement systems[6]
Inside diameter Inside circumference Sizes
(in) (mm) (in) (mm)
ISO
(Continental
Europe)
United States,
Mexico
United Kingdom,
Ireland,
Australia,
South Africa and
New Zealand
East Asia (China,
Japan,
South Korea),
South America
India Italy,
Spain,
Netherlands,
Switzerland
0.458 11.63 1.44 36.5 0
0.466 11.84 1.46 37.2 14
0.474 12.04 1.49 37.8 12 A
0.482 12.24 1.51 38.5 34 A+12
0.49 12.45 1.54 39.1 1 B 1
0.498 12.65 1.56 39.7 1+14 B+12
0.506 12.85 1.59 40.4 1+12 C 0.4
0.514 13.06 1.61 41.0 1+34 C+12 1 1
0.522 13.26 1.64 41.7 2 D 2 2 1.7
0.53 13.46 1.67 42.3 2+14 D+12 2.3
0.538 13.67 1.69 42.9 2+12 E 3 3 2.9
0.546 13.87 1.72 43.6 2+34 E+12 4 3.6
0.554 14.07 1.74 44.2 3 F 4 4.2
0.562 14.27 1.77 44.8 3+14 F+12 5 5 4.8
0.57 14.48 1.79 45.5 3+12 G 5.5
0.578 14.68 1.82 46.1 3+34 G+12 6 6 6.1
0.586 14.88 1.84 46.8 4 H 7 6.8
0.594 15.09 1.87 47.4 4+14 H+12 7 7.4
0.602 15.29 1.89 48.0 4+12 I 8 8 8
0.61 15.49 1.92 48.7 4+34 J 9 8.7
0.618 15.70 1.94 49.3 5 J+12 9 9.3
0.626 15.90 1.97 50.0 5+14 K 10 10
0.634 16.10 1.99 50.6 5+12 K+12 10 10.6
0.642 16.31 2.02 51.2 5+34 L 11 11.2
0.65 16.51 2.04 51.9 6 L+12 11 12 11.9
0.658 16.71 2.07 52.5 6+14 M 12 12.5
0.666 16.92 2.09 53.1 6+12 M+12 13 13 13.1
0.674 17.12 2.12 53.8 6+34 N 13.8
0.682 17.32 2.14 54.4 7 N+12 14 14 14.4
0.69 17.53 2.17 55.1 7+14 O 15 15.1
0.698 17.73 2.19 55.7 7+12 O+12 15 15.7
0.706 17.93 2.22 56.3 7+34 P 16 16.3
0.714 18.14 2.24 57.0 8 P+12 16 17 17
0.722 18.34 2.27 57.6 8+14 P+34 17.6
0.73 18.54 2.29 58.3 8+12 Q+14 17 18 18.3
0.738 18.75 2.32 58.9 8+34 R 19 18.9
0.746 18.95 2.34 59.5 9 R+12 18 19.5
0.754 19.15 2.37 60.2 9+14 S 20 20.2
0.762 19.35 2.39 60.8 9+12 S+12 19 21 20.8
0.77 19.56 2.42 61.4 9+34 T 21.4
0.778 19.76 2.44 62.1 10 T+12 20 22 22.1
0.786 19.96 2.47 62.7 10+14 U 21 23 22.7
0.794 20.17 2.49 63.4 10+12 U+12 22 23.4
0.802 20.37 2.52 64.0 10+34 V 24 24
0.81 20.57 2.54 64.6 11 V+12 23 25 24.6
0.818 20.78 2.57 65.3 11+14 W 25.3
0.826 20.98 2.59 65.9 11+12 W+12 24 26 25.9
0.834 21.18 2.62 66.6 11+34 X 26.6
0.842 21.39 2.65 67.2 12 X+12 25 27 27.2
0.85 21.59 2.67 67.8 12+14 Y 28 27.8
0.858 21.79 2.70 68.5 12+12 Y+12 26 28.5
0.866 22.00 2.72 69.1 12+34 Z 29 29.1
0.874 22.20 2.75 69.7 13 Z+12 27 30 29.7
0.882 22.40 2.77 70.4 13+14 Z1 30.4
0.89 22.61 2.80 71.0 13+12 31 31
0.898 22.81 2.82 71.7 13+34 Z2 32 31.7
0.906 23.01 2.85 72.3 14 Z3 32.3
0.914 23.22 2.87 72.9 14+14 33 32.9
0.922 23.42 2.90 73.6 14+12 Z4 33.6
0.93 23.62 2.92 74.2 14+34 34 34.2
0.938 23.83 2.95 74.8 15 35 34.8
0.946 24.03 2.97 75.5 15+14 35.5
0.954 24.23 3.00 76.1 15+12 36 36.1
0.962 24.43 3.02 76.8 15+34 36.8
0.97 24.64 3.05 77.4 16 37 37.4

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.[citation needed] 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.

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[7]

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

1. ^ "Jewellery – Ring-sizes – Definition, measurement and designation".
2. ^ S.W. Stratton, Director (Jan 24, 1921). Circular of the Bureau of Standards, No 43., Jewelers' and Silversmiths' Weights and Measures (Report). United States Department of Commerce. p. 39.
3. ^ British Standard 1283:1945
4. ^ British Standard 6820:1987
5. ^ Juwelier Limburg (21 November 2022). "Ring size measurement" (in German).
6. ^ "Convert Your Ring Size to MM : Ring Size Guide". Jewelove. Retrieved 2016-11-27.
7. ^ Do I Need Ring Sizing Beads? | Serengeti West Fine Jewelers