Blue john square silver stud earrings e114rthese simple and elegant studs boast two square shaped cabochon pieces of blue john stone that has been sourced directly from treak cliff cavern in castleton the stone sits within an exquisite sterling silver base completed by classic post and butterfly fastenings for easy wearrall 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