Silver Blue John Cushion Foxtail Necklet. N961. This exquisite necklace is part of our popular Foxtail collection and boasts a cushion shaped cabochon of rare Blue John stone that has been directly sourced from Treak Cliff Cavern in Castleton. The stone has been set on an intricately woven sterling silver foxtail chain that hangs gracefully around the neck. 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 necklaces on our website. Silver Blue John Cushion Foxtail Necklet. Blue John: 29mm x 29mm, total chain length 58cm.