From Discworld MUD Wiki
A penannular brooch.
Broad and hefty, this is an ornately figured ring of bronze with a single narrow gap. It fastens with a long bronze nail, its hammered loop free to slide on the ring, so that two layers of the wearer's mantle can pass through and be held firmly in place. The complex twisting designs look abstract at first glance, but focusing on the NoThingfjord amber gems shows them to be the eyes of looping serpents. It is in <condition> condition.
It is made of bronze and appears to be a piece of jewellery. It is in <condition> condition.
You heft the penannular brooch and guess that it weighs less than a pound.
When weighing it at a jeweller's balance:
The penannular brooch weighs 70 g.