Blue John Drop Silver Earrings. E094. These elegant drop earrings boast two stunning round pieces of rare Blue John stone that has been sourced directly from Treak Cliff Cavern in Castleton. The stone is set on the end of the sterling silver mount which hangs gracefully from the lobe which is fastened by classic butterfly fastenings. All our Blue John jewellery is designed and crafted within our very own workshops in Ashbourne, Derbyshire where a team of skilled craftsmen turn the raw Blue John stone into these stunning pieces of jewellery. You can find other matching Blue John jewellery and other Blue John earrings on our website. Sterling Silver and Blue John.