Spiral decorated Iron Age Scottish glass beads are a group of highly decorated objects about which very little is known. Despite considerable debate in the past, their technical complexity and elaborate design have always hindered the understanding of their method of production. The innovative application of X-ray micro-computed-tomography (μCT), with synchrotron light, rendered detailed information of the internal structure of selected artefacts, allowing for the investigation of features relating to manufacture. The 3D imaging not only permitted the identification of characteristic features and markings typical of specific low temperature glass-working techniques, but also added to the evidence for local manufacture and allowed conclusions to be drawn on the pyro-technological development of the ancient communities that produced them.