Blue john oval silver cufflinks cl512 these stylish cufflinks boast stunning oval shaped pieces of cabochon blue john stone that have been directly sourced from treak cliff cavern in castleton the stone is set within a sterling silver base and completed by twist fastenings 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 jew