Blue john round silver cufflinks cl511 these stylish cufflinks boast a stunning round cabochon piece of blue john that has been directly sourced from treak cliff cavern in castleton the stone is set within a sterling silver base which has been completed with a twist fastening for easy wear all our blue john jewellery is designed and crafted within our very own workshops in ashbourne derbyshire where a team of skilled craftsmen turn the raw blue john stone into these sophisticated pieces of