Do you know why we say "Jet Black"?

Raw Whitby Jet

Jet is a black semi-precious gemstone which is actually fossilised wood.

Whitby jet was formed from trees very similar to the modern day monkey-puzzle tree but which lived about 180 million years ago during the Jurassic period. When the trees died they fell into water in swamps or rivers and some were washed into the sea. The trees would become waterlogged and sink to the bottom, there to be slowly covered by thick layers of sand and mud. Over the millions of years between then and now the tree remains were compressed by the massive pressure of hundreds of metres of covering which accumulated. As the sand slowly changed into sandstone, the mud changed into either shale or mudstone and the some of the tree remains changed into the substance we know as jet. Movement and erosion of the earth's surface has finally brought the Jurassic rocks back to the surface in some areas. The best place in Britain for finding jet is the Yorkshire coast around the Whitby area where small pieces can be found on the sea shore at low tide.

Victorian Whitby Jet Choker

Because jet is easy to carve (hardness 3-4 on Moh's scale) and has a beautiful black sheen, it has been used as a decorative stone since stone-age times. The Romans used jet for decorative purposes and used the name gagates for this stone. Jet is not unique to Britain, some of the earliest artifacts have been found in Germany, but it can also be found in Spain and in Utah and Colorado in the United States.

Whitby Jet Hexagonal Brooch Whitby Jet Carved BroochBar BroochWhitby Jet Cross BroochWhitby Jet Cameo

With the growth of rail travel and interest in 'holidaying' on the coast, Whitby became a popular seaside haunt for the Victorians. The Victorians liked to collect souvenirs of their holidays and from Whitby the treasure had to be a piece of jet, the most popular item being a brooch, sometimes carved with a name or love message. As this interest grew so did the Whitby jet industry, in the 1830's there were two jet shops in Whitby and by the 1870's this had grown to over 200 shops. When Prince Albert died in 1861 Queen Victoria entered into 'severe mourning' and would allow only jet black jewellery to be worn at court. The Victorian people followed this fashion and soon jet jewellery became the height of fashion.

Whitby Jet Necklace BeadWhitby Jet Necklace BeadWhitby Jet Necklace BeadWhitby Jet Necklace Bead

Because of its low hardness jet could be shaped and carved by hand and earlier examples were produced this way using home-made tools and files. Mechanisation soon reached the jet industry and after initial rough shaping with chisels, jet pieces would be shaped and carved using treadle driven rotating wheels made of lead and coated with abrasive powder. Wheels coated with woollen material or chamois leather were used along with polishing powder to obtain the final finish. Lathes were used to mass produce round beads for the chunky Victorian necklaces which would then be patterned using the lead cutting wheels.

Whitby Jet 3 Row NecklaceWhitby Jet Watch ChainWhitby Jet Bead Necklace

Before the boom in jet sales most of the jet sold had been picked up on the seashore. However demand for jet in Victorian times far outstripped supply and mining for jet became common. Remains of the old jet mines can still be seen along the Yorkshire coast from Staithes to Robin Hood's Bay. Jet was also mined inland where there were less problems with tides and high cliffs. Modern day demand is less than in Victorian times, mining for jet is no longer economical, and demand is now met once again by the seashore.

Whitby Jet Earrings Whitby Jet Cross PendantModern Whitby Jet Pendant with AmmoniteWhitby Jet PendantWhitby Jet Jet PendantWhitby Jet Jet Earrings

Jet jewellery is still produced in Whitby. The modern jewellery is less 'chunky' than the Victorian jewellery and consists mainly of pendants, earrings and brooches, usually with silver fittings.

Beware of fakes

Plastic BroochBog Oak BroochVulcanite Brooch

The brooches pictured above are all fakes. The one on the left is modern plastic, the centre one is Irish bog oak with a carving of Whitby Abbey and the one on the right is vulcanite. All three look like genuine jet but when examined closely do not have lustre or feel of the real article.

Glass NecklacePlastic Necklace

The necklaces pictured above are also fakes. The one on the left is 'French Jet' (glass), detectable by its very cold feel compared with the real thing. The necklace on the right is modern plastic, the clue to its identity are the thin moulding marks on each bead, genuine jet is carved or cut on a lathe and will not have the marks left by a mould.

The moral of the story is BE CAREFUL, all that is black is not jet.

For help identifying genuine jet CLICK HERE


 

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