Whitby Jet And Diamond Necklace P1798 These beautiful necklace features a marquise shaped piece of hand cut Whitby Jet, with a diamond surround, the stones have been set within 18ct yellow gold. Hand crafted by our skilled jewellery craftsmen to reveal the natural beauty of the Whitby Jet gemstone with this stylish design, there are matching items available. Using only the finest quality diamonds their total weight for the pendant is 0.14ct.