Silver Blue John Oval Marcasite Ring. R818. This stunning statement ring boasts a striking oval shaped cabochon of rare Blue John stone that has been sourced directly from Treak Cliff Cavern in Castleton. The stone has been placed within an exquisite oval sterling silver setting detailed with dazzling marcasite stones, giving a sophisticated sparkle to the piece. The ring is completed by a classic sterling silver band with double stranded shoulders. 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 stunning pieces of jewellery. You can find other matching Blue John jewellery and other Blue John rings on our website. Sterling Silver and Blue John