9ct Yellow Gold Blue John Toscana Long Marquise Necklace. P1613. This striking necklace is part of our Toscana collection and features a stunning marquise shaped cabochon of rare Blue John stone which has been sourced directly from Treak Cliff Cavern in Castleton. 9ct Yellow Gold surrounds the Blue John stone. The pendant sits gracefully on an 18 inch, 9ct Yellow Gold chain that is 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 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. Dimensions: 40mm