Distinctive obsidian artefacts from West New Britain appear sometime before 3950 cal BC and terminate abruptly at 1650 cal BC. We propose that they had a wide range of meanings for their users and functioned in both utilitarian and ceremonial contexts, similar to more recent ground stone axes from Highland New Guinea. They therefore represent the earliest evidence for valuables in Papua New Guinea. Here we draw together studies of the technology, spatial distribution and chemical sourcing of the artefacts, along with considerations of fragility and brightness, to evaluate competing models for their function as utilitarian items and as exchange goods. Whereas many artefacts were probably useful tools integrated within a mobile settlement pattern, others were clearly reserved for special functions, and many may have operated in both the utilitarian and ceremonial spheres.