What is a triblet in jewellery making?
By Jared James · Last updated 21 May 2026
Definition
A triblet is a tapered, cylindrical metal rod used in jewellery making to shape, round and size rings. The ring is slipped over the wider end and hammered or pressed down to the position that corresponds to the desired diameter, using the gradual taper to get an accurate and even round shape. Triblets are usually made from steel and marked with ring sizes along their length, and they are an essential bench tool for any jeweller working with rings. The word is also sometimes spelt triblet or mandrel, with ring mandrel being the more common modern term.
Frequently asked questions
- What is the difference between a triblet and a ring mandrel?
- They are essentially the same tool; triblet is the older, more traditional term used in British and European jewellery making, while ring mandrel is the more widely used modern name in most English-speaking contexts. Both describe a tapered steel rod used to shape and size rings on the bench.
- How do jewellers use a triblet to size a ring?
- The ring is placed over the narrow end of the triblet and pressed or tapped down with a mallet until it sits at the size mark corresponding to the required size. The round, tapered shape of the triblet ensures the ring stays perfectly circular during the sizing process. The triblet is usually held in a vice or triblet stand for stability.
- What materials are triblets made from?
- Most jewellers' triblets are steel, which is hard enough to withstand repeated hammering without deforming. Some triblets are made from aluminium for lighter bench work. Grooved or oval triblets also exist for shaping non-circular ring shanks like comfort-fit or oval profiles.
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