According to the donor these earrings were originally owned by her grandmother, Mary Howard (Wildes) Chase (b. 1820). By the mid nineteenth century the size of jet jewelry increased. Pairs of bracelets, drop earrings, and chunky link necklaces were carved entirely of jet without the use of secondary materials such as gold or pearls. This fashion continued until the 1880s when the supply and demand for jet began to decrease. This decline was evident in the dramatic reduction of the number of workers in the town of Whitby, England, the worldwide center of jet production. In the early 1870s Whitby supported 1,500 workers; by the mid 1880s only 300 remained. The use of alternative materials, such as onyx, French jet, vulcanite, and gutta percha also contributed to the decline of jet.
Source: historicnewengland.org