Most collectors of Roman coins can easily identify a large number of Emperors by their portraits, at least for early and mid Imperial times.  Can you name the emperor based only on a written description of their physical attributes?  In the July 1928 issue of Studies in Philology, author H. V. Canter published descriptions of various Roman emperors' physical attributes based solely on contemporary and near-contemporary written histories.  He did not use coins, statues, or other physical objects.  The paper, Personal Appearance in the Biography of the Roman Emperors, is in Volume 25, Number 3, pp. 385-399.