National Museum experts identified the ring

The National Museum's Dr Mark Redknap said it is the second ring of its type to be found in Wales recently.

"It provides a fine illustration of late medieval devotion and adoption of the popular sacred image of Mary," he said.

In August, another 15th century ring, a silver clothing pin and an ancient brooch were discovered by enthusiasts with metal detectors in Pembrokeshire and Swansea Bay .

Stephen Thomas, from Pyle, struck lucky and found buried beneath the layers of sand and clay on Swansea beach an ancient brooch - the only one of its kind in Wales.

It was analysed at the National Museum of Wales in Cardiff and was found to contains 3.34 grammes of silver and dated as being more than 300 years old.

The Treasure Act 1996 rules that all objects containing over ten per cent of silver and gold more than 300 years old when found are treasure.

If museums later acquire the objects, the finders are normally rewarded their full market value.