These buckles were common throughout Northern Europe in a variety of sizes. They have appeared archaeologically as early as 1350 and lasted at least until the 16th.
These are also replacement pieces for the Complete Rapier Set sold here. The silver version has a silver finish it is not real silver.
Similar designs can be seen in the Portable Antiquities Scheme. https://finds.org.uk/database/artefacts/record/id/963939
