Sterling Silver Blue John Marquise Ring. R404. This contemporary ring is part of our Heritage handmade jewellery collection and features a stunning marquise shaped piece of Blue John stone that has been sourced directly from Treak Cliff Cavern in Castleton. The stone is framed simply within a Sterling Silver setting and completed with a classic Sterling Silver band. 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 rings on our website. Dimensions 6 x 11mm stone.