Silver blue john oval marcasite ring r818 this stunning statement ring boasts a striking oval shaped cabochon of rare blue john stonethat 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 cr