18ct Yellow Gold Whitby Jet 0.21 Carat Diamond Cushion Ring. R594. This gorgeous ring showcases a stunning hand carved square Whitby Jet gemstone which has been sources directly from the north east coast of Yorkshire and is encased in an 18ct Yellow Gold setting that is pave set with 0.21 carats of sparkling white Diamonds.  All our Whitby Jet jewellery is designed and crafted within our very own workshops in Derbyshire where a team of skilled craftsmen transform the natural Jet into these stunning pieces of jewellery. You can find other matching Whitby Jet jewellery and other Whitby Jet rings on our website. 18ct Yellow Gold Whitby Jet 0.21 Carat Diamond Cushion Ring. Whitby Jet stone 10x10mm, Width of band 1.6mm.