Fatimid art is known for the production of luxury artifacts, particularly rock crystal vessels. The appearance in 2008 of the Francis Mills Ewer, which seemed to belong to a famous group of 6-8 rock crystal ewers attributed to Fatimid Egypt, prompted an investigation of the techniques used to carve them. A comparison of the carving technique of the Francis Mills Ewer with that of the other members of the group offers the best criterion for determining whether the new ewer belongs to this group. To this end, the traces of manufacture (mainly polishing and carving) were analysed on a group of fourteen artifacts. The topography of the surfaces has been measured with a confocal rugosimeter using silicon replicas. To identify and characterise the multi-scale wear signature and the traces left by the tools, a Fourier isotropic filtering technique was applied. Using these complementary methods, we were able to confirm that the Francis Mills Ewer belongs to the Fatimid group.