Introduction
The black spacer plate necklaces and bracelets of the Early Bronze Age (Figure 1) are among the most technically accomplished prestige items of this period in Britain and Ireland. There has been much debate over the years as to whether these artefacts and other prehistoric black jewellery and dress accessories are the product of specialist jetworkers based around Whitby in North Yorkshire — Britain’s only significant source of jet. As early as 1916, for example, Callander was arguing that the Scottish finds had been made using locally available materials — cannel coal, shale and lignite — rather than Whitby jet. There has also been much confusion over the identification of these various materials. Flirthermore, the conservation of newly discovered jet and jet-like artefacts can be problematical, and the correct identification of raw material is important in determining the best method of treatment.