The article aims to be the first of a series about mosaic crests in tomb stones in Roman medieval churches. This contribution is about the tombal stone of Giuliano Porcari in the Roman church of San Giovanni della Pigna, dated to the end of the 13th century. It presents historical sources (in particular, a reproduction of the 16th century), then focuses on the mosaic frame in red and green porphyry and to the crest of the Porcari family, which actually appears strongly damaged by past restorations.