Sarah Caldwell Steele is widely considered the world’s leading expert in black gemstone identification. She was awarded Fellowship of the Gemmological Association of Great Britain in 2013, and Diamond Fellowship in 2015. She holds a first degree in geology from the University of Durham and has returned to Durham in 2019 as a doctoral researcher in archaeology. Her multidisciplinary and multiperiod PhD thesis focuses on the gemmological classification, identification and interpretation of black artefacts within the archaeological record, focusing in particularly on country-of-origin analysis for the Jet Group.