Sterling Silver Blue John and Marcasite Six Point Star Stud Earrings. E1638. These simple and stylish stud earrings boast two small round pieces of rare Blue John stone that has been sourced directly from Castleton, Derbyshire. The stone is set within an exquisite sterling silver star design that has been embellished by marcasite stones, adding an unmissable sparkle to the piece. The earrings are completed by classic post and butterfly fastenings for easy wear. All our Blue John jewellery is designed and crafted within our very own workshops in Ashbourne, Derbyshire where a team of skilled craftsmen transform the natural 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.