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

A collection of 14 Chinese jades of the Museum of Oriental Art, Turin (Italy), was stylistically described and studied at the optical microscope in incident/grazing light, to detect manufacturing marks and reconstruct production techniques (handcrafted or mechanical) without risking removal of materials. A non-invasive multi-analytic protocol (p-XRF/PCA, FTIR and µ-Raman spectroscopies, µ-X-ray diffraction) was applied to characterize materials and conservation. Eight artefacts are made of nephrite – consistently with the archaic Chinese jades composition, though insufficient to assess legitimacy. The recurrence of revealing manufacturing marks/iconographies allowed supporting these items genuineness. Six artefacts revealed different lithologies, sometimes with hardness/tenacity significantly lower than jades. For some, distinctive technological marks suggest that the choice of atypical materials was either dictated by specific necessities or consequent to the artefacts use or interment; in few cases, doubts arose about legitimacy. This study provides an archaeometric perspective for evaluating material inconsistencies between museum artefacts and archaeological specimens.