Two silver plates in the collection of the J. Paul Getty Museum were studied by non-destructive x-ray fluorescence spectroscopy, inductively-coupled plasma-mass spectrometry, x-radiography, optical metallography, electron microprobe analysis and lead isotopic composition. One plate depicts a scene of philosophical discourse (the Philosopher plate) and the other an aged fisherman with his catch (the Fisherman plate). Both plates have designs on the fronts made not by repousse but by a combination of working and annealing followed by carving to shape. Technical and analytical results are described which support the attribution of a date in the early centuries AD. There are several differences between the two plates, such as the way in which the footring has been made and attached. Both, however, have thick corrosion crusts and have suffered intergranular corrosion. Determination of trace elements, such as zinc and gold, together with the method of manufacture suggests that both plates are ancient. Lead isotopoc data for the two plates is different, with the Philosopher plate showing a close relationship to other Byzantine objects, even though a Renaissance date had been suggested.