18ct white gold blue john 012ct diamond tear drop ring r591 this elegant ring boasts a stunning cabochon tear drop shaped piece of rare blue john stone that has been sourced directly from the derbyshire blue john cavern in castleton the stone is set within exquisite 18 carat white gold and surrounded by mesmerising 012 carat diamonds the ring is completed by a classic white gold band all our blue john jewellery is designed and crafted within our very own workshops in ashbourne derbyshire