Jet
from the Antique Jewelry University
Jet is a fossilized wood that is derived from driftwoods on - mainly - the north-eastern coast of England, UK. In particular the area around the fishing port Whitby, Yorkshire where it has been mined from the cliffs as early as 1500 BC[1]. During the Roman occupation this area was mined for this velvety black gem but it was not until the 19th century that excavations in the area became extensive.
During the whole part of the 1800's jet was used in mourning jewelry due to its color, as were many other black materials,[2] but it was after the death of Prince Albert, in 1861, that it became a fashion item. Queen Victoria went in mourning upon the death of her consort and remained so for the next 40 years and the color black remained fashionable until her own depart in 1901. Jet went out of style soon after.
Jet has a velvety luster which can take polish very well. With a hardness of 4 it is relatively soft but many items have survived in good condition from the Victorian period. The mining areas of this intense black material were, apart from the main source Whitby, in Spain and France.
When rubbed jet can produce electricity and it is due to this property that it has also been given the name black amber. Friction may also produce a typical coal odor, and it is indeed strongly associated with the brown coals found in the north of the UK. Jet reacts well to heat and chemical attacks, so they should be avoided at all times. Heat will cause it to burn, while chemical attack may cause it to loose its luster. As a positive consequence, a hot needle test can be used to discriminate jet from a look-a-like as vulcanite or plastics.
Other black materials which were used in mourning jewelry and which may resemble jet include:
- Vulcanite - a black or red vulcanized rubber with sulfur, invented in 1839 by Charles Goodyear.
- French jet - a black glass.
- Gutta-percha - a dark rubber from tropical trees, used from the mid 19th century.
- Onyx - a black stained chalcedony.
- Fer de Berlin - iron jewelry stained black through the use of linseed oil.
- Plastics - especially bakelite from around 1910.
- Black enamel
| Gemological information for jet | |
|---|---|
| Color | Black |
| Crystal structure | Amorph |
| Refractive index | ~1.6 |
| Durability | Not very durable, brittle |
| Hardness | 4 |
| Treatments | None known |
| Country of origin | England |
| Jet care | |
| Ultrasonic cleaning | Not safe |
| Steam cleaning | Not safe |
| Warm soapy water | Safe |
| Chemical attack | Avoid |
| Light sensitivity | Stable |
Notes
Sources consulted
- Bennett & Mascetti, David & Daniela. Understanding Jewellery. Antique Collectors' Club. 1991.
- Mortimer, Thomas. A General Dictionary of Commerce, Trade, and Manufactures. R. Phillips, London, UK. 1810.
- Robert Webster/ B.W. Anderson. Gems Their Sources, Descriptions and Identification 4th Edition. 1990.