Jet has been widely used in the past for jewellery but was just one of a range of black lithic materials employed. When worked into small objects these materials can be visually indistinguishable, yet discrimination is important because of the restricted occurrence of jet. X‐ray fluorescence (XRF) is a rapid non‐destructive discriminatory technique, but not all samples are clearly classified, and inhomogeneity may pose problems. A reassessment of the use of XRF is reported. Other techniques considered include electron spin resonance, infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy and X‐radiography. These were tested on geological materials to define an effective methodology for archaeological material. The recommended approach is a combination of XRF and X‐radiography, although preliminary Fourier transform infrared results showed promise. The X‐ray techniques were tested on Romano‐British assemblages from Catterick a