Assessment of manufacturing processes and materials characterization on a collection of ancient Chinese Jades

A collection of ancient Chinese jades of the Museum of Oriental Art, Turin (Italy), was studied with an optical microscope in incident/raking light to detect production marks and reconstruct manufacturing techniques. A non-invasive, multi-analytic protocol (p-XRF/PCA, FTIR and mu-Raman spectroscopies, mu-X-ray diffraction) was applied to characterize the materials and state of conservation. Eight were confirmed to be nephrite artefacts, consistent with the composition of archaic Chinese jades, though there was insufficient evidence to assess an attribution. Yet this evidence - coupled to manufacturing marks and stylistic features - supports their authenticity. Six are made of other lithologies/materials, with hardness/tenacity lower than jades. Technological marks suggest that the choice of such materials might depend on specific reasons, consequent to use or interment. Doubts arise about the genuineness of five items, due to odd manufacturing signs and/or stylistic inaccuracies. This study shows the fundamental role of archaeometry in assessing the authenticity of historical artefacts, supporting the dissemination activities promoted by museums.