In the east intrados of the chapel are medallions with busts of Christ, at the centre, and of six apostles, including Peter and Paul, identified with inscriptions bearing their names.
Saint Paul is depicted according to his traditional features, with a receding hairline touched by a small tuft of hair, a long dark beard, large thoughtful eyes – instruments of divine contemplation. The mosaic is realised almost like a highly refined painting, through lines that define the volumes of the face thanks to the juxtaposition of tesserae in delicate hues. Blue-grey, light blue and white tesserae define the volumes of the tunic, while the more illuminated folds of the cloak is rendered in brown and ochre tesserae. The portrait of the apostle-philosopher emerges from an indigo background, and is surrounded by an aura of lighter tesserae.