Sterling silver blue john marcasite round beaded edge stud earrings e1633 these simple and stylish stud earrings boast two round cabochons of fine blue johnstone that have been sourced directly from the treak cliff cavern in castleton the stones are set within simple sterling silver frames that have been embellished by marcasite stones which add a vintage stylesparkle the earrings are completed by classic post and butterfly fastenings for easy wear all our blue john jewellery is designed