18ct white gold whitby jet 021ct diamond square cushion ring r594 this statement ring features a stunning cushion shaped cabochon of the finest whitby jet stone sourced directly from the north east coast of yorkshire the beautiful 18ct white gold frame is embellished by dazzling 021 carats of brilliant cut diamonds 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 designe