The inscription – which reads +SECRETVM . RICARDI – shows the seal was created specifically for a man called Richard.
He would have used it to make a mark in hot wax to seal his letters and documents.
Richard appears to have specifically chosen the carved gemstone, known as an intaglio – possibly as a way of showing he had an understanding of the Classical world, according to Miss Rogerson.
She said: “It definitely would have been an indicator of the owner’s social status as a way of saying, ‘I have the means of obtaining something from a far gone time and place’ and indicated they were quite important – or saw themselves as quite important.”