A Whitby jet necklace, the lozenge shaped facetted graduated beads alternating with round beads, to a metal parrot clasp, total length 1360 mm., Whitby jet is a natural organic gemstone formed from the compressed wood of the monkey puzzle or araucaria tree, found along a two mile stretch of coastline between Robin Hood's bay and Boulby, nearby to Whitby, north Yorkshire. Whitby jet gemstone is formed over 186 million years ago.