Blue john ring curved triangle silver r407 this simple and sophisticated ring is part of our heritage handmade jewellery collection and boasts a stunning curved triangle shaped piece of blue john stone that hasbeen sourced directly from treak cliff cavern in castletonthe stone is framed within an exquisite sterling silver setting and completed with a classic sterling silver band all our blue john jewellery is designed and crafted within our very own workshops in ashbourne derbyshire where