Silver blue john marcasite square ring r751 this stunning ring boasts a delicate squareshaped cabochon of rare blue john stone that has been sourced directly from the treak cliffcavern in castleton the stone is placed within an exquisite sterling silver setting embellished by dazzling marcasite stones bringing a sophisticated sparkle to the piece the ring is completed by a classic sterling silver band all our blue john jewellery is designed and crafted within our very own workshops in as