Sterling silver blue john pear ringr408 this simple and stylish ring boasts astriking pearshaped cabochon of the finest blue johnstone that has been sourced directly from the treak cliff cavern in castleton the stone is simply but classically framed insterling silver on a 3mm wide sterling silver band all our blue johnjewellery is designed and crafted within our very own workshops in derbyshire where a team of skilled craftsmen turn the raw blue john into these stunning pieces of jewel