The insertion of decorative glass elements in reliquaries and jewellery was a widely diffused practise in Italy between the 14th and 15th century. Not so frequent, yet significant are the examples of glass pieces inserted in frescoes or paintings. Important specimens of this kind are to be found in the frescos painted in the Capella degli Scrovegni in Padua and in St. Francis' Basilica Inferiore in Assiai, and in Giotto's Cross in Santa Maria Novella in Florence. During recent restoration works it was possible to examine some decorative glass pieces used by Giotto in Florence and Padua and by the Maestro di San Franesco whom the painting of the nave in the Basilica Inferiore in Assisi is attributed to. The present work reports on the result of the analyses performed on the glass pieces and the metal films applied onto them, with the aim of drawing information on their production techniques, provenance and preservation state. At least for the glass items used in the Capella degli Scrovegni was it interesting to assess a similarity to Venetian artefacts, for a flourishing glassmaking activity already existed at that time in the isle of Murano
