Toadstones are the button-like palatal teeth of lepidotes, an extinct genus of ray finned fish from the Jurassic and Cretaceous periods.
However, throughout the Middle Ages and into the 18th century they were thought to be found in the heads of living toads and were highly prized for their supposed magical properties. In particular, it was believed they could be used as an antidote to poison and were commonly worn about the personal as amuletic rings and pendants.
This example was found by head of department Catriona Smith in a box of mixed jewellery. It is set in a high carat gold shank in the Tudor or early Stuart period and pierced to the underside in the expectation that the stone’s protective powers would be increased on contact with the wearer’s skin. At some point in its life the ring had become too small for the owner to wear so instead it was fitted to a chain.