Thought I would post up some information on the working of Whitby Jet, as it is quite difficult to get good info on this subject. We learned by trial and error (there was and still is a lot of error….)
The most important part of working Whitby Jet is the selection of the Jet itself. There are two types of Whitby Jet, soft Jet and Hard Jet. Hard Jet is jewellery grade and is the type you should use. It can be difficult to tell the difference between the two types by just looking, however there is a easy test you can perform –
Take your piece of jet and gently rub it on some wet and dry sandpaper, the colour of the streak it leaves behind determines whether it’s good quality or poor quality (soft jet).
As you can see from the picture I have tested two bits of Whitby Jet, one being poor quality soft jet the other good quality hard jet. The darker streak at the top indicates that the piece tested is soft jet, while the bottom streak indicates good quality Whitby Jet. The rule of thumb is the lighter the streak the better the quality!
Another important factor to take into account before starting work on your piece is whether the Jet has any flaws in it, these come as inclusions within the Jet. The inclusions are normally pyrite or calcite. Usually these inclusions are easy to spot as they show up as faint lines running through the jet, however sometimes you can spend an age getting a piece shaped to perfection only to discover an inclusion during the final polishing stage (frustrating to say the least!) Keep a close eye on your work through all the stages until completion, and your fingers crossed 😀