18ct Yellow Gold Blue John 0.03ct Diamond Marquise Necklace, PUNQ0005174. This elegant pendant features a faceted marquise shaped Blue John gemstone sourced directly from Castleton, Derbyshire. The gorgeous Blue John is set into 18ct yellow gold and finished with three delicate diamonds which are bezel set totalling 0.03ct. A fabulous addition to any jewellery lovers collection. This item is supplied complete with an 18 inch 18ct yellow gold chain. At C W Sellors, we have an expert team of gemstone and diamond specialists who handpick and grade each jewel to meet our high standards and a team of talented in house designers who combine their talents to bring you our exclusive Precious Gemstone collection. You can find other Blue John pieces online and in store to complement this necklace. All articles purchased from C W Sellors are lovingly and securely dispatched with our elegant jewellery packaging.