Millions of years in the making.
Jet is made from the fossilised remains of the Araucaria (Araucana) species of tree - a modern descendant being the distinctive Monkey-Puzzle tree. This tree existed in vast forests around the world throughout the Jurassic period and makes up a proportion of the Whitby Lias rocks.
The North Yorkshire Coast of England is famous for its impressive shale cliffs towering hundreds of feet above the North Sea. These cliffs are rich with fossils and the many different strata are visible from standing on the beach looking up at the rocks.
When an Araucaria tree eventually died it would fall into the surrounding rivers and bogs and slowly make its way towards the sea, breaking up along the way. After becoming waterlogged it would sink to the seabed, where over time layers of sediment and decaying organisms would bury it, compressing and starving the wood of oxygen under millions of tons of rock, the North Yorkshire coastline benefits from ideal conditions which allow a chemical shift to occur, and over the next 180 to 200 million years the transition would take place from the wood into the rich resource of Whitby Jet.
Whitby Jet has a hardness of 2.5 to 4 on the Mohs scale of hardness making it an easy material to carve or cut. It also has a low specific gravity allowing larger brooches and beads to be worn in comfort - as seen in the Victorian era when large items were at the height of fashion.
Any research will show jet can be found in many countries throughout the world including Spain, USA, China, Turkey. Russia and Australia. However, it is not until you hold a piece of Whitby Jet alongside any of the aforementioned material you immediately notice the quality. Alternative jet lacks the lustre of hard Whitby Jet and has known to crack and break over time. It is also a common mistake, mostly before a piece of jewellery is held, that jet appears to be onyx.