18ct White Gold Blue John Oval 0.08 Carat Diamond Pendant Necklace. SH5_18BJ. This stunning pendant boasts a striking oval shaped piece of multi-faceted 19.89 carat Blue John stone that has been sourced directly from Castleton, Derbyshire. The Blue John stone is claw set within 18ct white gold and paired with a dazzling 0.08 carat diamond.  The pendant hangs from a fluid 18 inch long 18ct white gold chain. 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 necklaces on our website. 18ct White Gold Blue John Oval 0.08 Carat Diamond Pendant Necklace. 18 inch long 18ct white gold belcher chain (42089).