There is not one consistent ring size for rings. There are at least six different groupings. The UK, New Zealand and Australia (Commonwealth countries) use a letter system from A to Z while the US, Canada and Mexico use a numbering system, from 1 for the smallest size up to 14. France and Russia use numbering from 46 1/2 to 67 1/2 and Germany goes from 13.5 to 22. Other European countries like Italy, Spain, the Netherlands and Switzerland use the numbers 1.5 to 27.5. The Japan, China, India and South America sizing numbers are similar, ranging from 1 to 26.

It sounds a mess but some of the sizing methods make sense. Some are based on the inner circumference of the ring, others on the outer circumference. One is based on the inner diameter of a ring, another on the outer.

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Ring sizer

There is an international standard for ring sizes (ISO 8653:2016) which is used by France, Germany, Austria, Iceland, Belgium, the Scandinavian countries and a few other European countries. It has two measurements, one used by manufacturing jewellers which is the inner circumference measured in millimetres and one used for determining the size of a customer’s ring finger which is the inner diameter, also in millimetres. So the first measurements will range for 36.5 to 68.5 while the second set of measurements will range from 13 to 22.5. So, for example, the French size of a ring is the actual circumference of the inside of the ring in millimetres.  

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Ring sizer (or ring mandrel) showing US and UK sizing scales.

The letter system used by the UK and other Commonwealth countries is known as the Wheatsheaf standard. It was developed and patented in 1920 by a jeweller called Joesph Pepper.  It later became the UK ring sizing system and was introduced as a standard in 1945, British Standard 1283:1945, and updated in 1987 by British standard 6820:1987.

This all sounds too difficult but there are a number of comparison charts of the different ring sizing systems which can simplify the process. In my next post, I will discuss how to measure a ring size.