How do I use a ring mandrel or ring gauge to check finished ring sizes?

A ring mandrel is a tapered rod that measures the inside size of a ring, and a ring gauge is a set of sample rings. Slide the ring gently onto the mandrel until it stops, read the size and compare with the order. Check a sample of each size.

The tools

Our advice A mandrel is a graduated cone. A gauge is a set of fixed rings in different sizes. Both measure the inner diameter, but they differ in how they behave with different band shapes.

Technique

1. Clean the ring and the mandrel.
2. Push the ring gently down the mandrel without forcing it.
3. Read the number at the point where it stops.
4. For a gauge, find the sample ring that fits the same way.
5. Repeat for several rings of the same size.

Things to watch

• Comfort-fit and wide bands may read differently from flat narrow ones
• A ring that is slightly out of round gives inconsistent readings
• Tight stones or settings can affect how the ring sits

It depends Sizing standards differ between countries, and tolerances differ between factories. Agree which size system you use and how much deviation is acceptable.

Compare with specification

Our advice Record readings and compare them with the order. If many rings are off by the same amount, the factory probably used a different reference, and you should raise it.

Calibrate

• Check your own mandrel against a trusted standard
• Replace worn or damaged gauges

Record

• Log the size ordered and the size measured

A practical routine

Our advice At each delivery, pick a handful of rings from each size and measure them on the mandrel. Record the readings next to the ordered size, and compare with the previous batch. Over a few orders you will see whether a factory is consistent, and you can raise any drift while it is still small.

Our advice Record the readings next to each batch, so later orders can be compared.

Uncertain We cannot say what tolerance suits your rings. Set one in your specification.

Related reading: What ring size should I buy for a surprise gift? · How to Find Your Ring Size at Home (Free Printable Method)

Sources

No external standard governs this question, so this answer is editorial advice from the ZKZ team and is labelled that way.

Fact = stated by the cited source. Our advice = editorial recommendation. Uncertain / it depends = limits of what can be said in general.