Sterling silver blue john four petal flower necklace p2095 this simple and stylish necklace boasts a stunning round cabochon piece of rare blue john stone that has been sourced directly from treak cliff cavern in castleton the stone is set within an exquisite sterling silver flower design that hangs gracefully from an 18 inch long sterling silver chain completed by a classic bolt ring clasp for easy wear all our blue john jewellery is designed and crafted within our very own workshops in ash