Silver Whitby Jet Marcasite Garnet Dragonfly Brooch. M329. This stunning dragonfly brooch is handmade in sterling silver and features a beautifully hand carved Whitby Jet gemstone, sourced directly from the north east coast of Yorkshire, which are surrounded in a silver frame accented with sparkling Marcasite gemstones and deep red garnets set into the eyes and tail. It is an exquisite and detailed piece which would make a beautiful gift. All our Whitby Jet jewellery is designed and crafted within our very own workshops in Derbyshire where a team of skilled craftsmen turn the raw Jet into these stunning pieces of jewellery. You can find other matching Whitby Jet jewellery on our website. Silver Whitby Jet Marcasite Garnet Dragonfly Brooch. 39x33mm, Whitby Jet 8x6mm.