Sterling Silver Whitby Jet Marcasite Butterfly Brooch. M325. This stunning butterfly brooch is handmade in sterling silver and features four beautifully hand carved Whitby Jet gemstones, sourced directly from the north east coast of Yorkshire, which are surrounded in a silver frame accented with sparkling Marcasite gemstones. 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 Ashbourne, Derbyshire where a team of skilled craftsmen transform the natural Whitby Jet stone into these stunning pieces of jewellery. You can find other matching Whitby Jet jewellery online and in store. Silver Whitby Jet Marcasite Butterfly Brooch. 32x47mm.