Sterling Silver Blue John Inlay Band Ring R003 This simple band ring features a highly polished rectangular cabochon of fine Blue John stone that has been sourced directly from the Treak Cliff Cavern in Castleton. The stone has been placed within a classic sterling silver band. All our Blue John jewellery is designed and crafted within our very own workshops in Derbyshire where a team of skilled craftsmen transform the natural Blue John into these stunning pieces of jewellery. You can find other matching Blue John jewellery and other Blue John rings on our website. Blue John: 11mm x 4mm.