The stone of the ring2899 which is now shown as that of Polycrates, is untouched and without engraving. In the time of Ismenias, long2900 after his day, it would appear to have become the practice to engrave smaragdi even; a fact which is established by an edict of Alexander the Great, forbidding his portrait to be cut upon this stone by any other engraver than Pyrgoteles,2901 who, no doubt, was the most famous adept in this art. Since his time, Apollonides and Cronius have excelled in it; as also Dioscurides,2902 who engraved a very excellent likeness of the late Emperor Augustus upon a signet, which, ever since, the Roman emperors have used. The Dictator Sylla, it is said, always made use of a seal2903 which represented the surrender of Jugurtha. Authors inform us also, that the native of Intercatia,2904 whose father challenged Scipio Æmilianus,2905 and was slain by him, was in the habit of using a signet with a representation of this combat engraved upon it; a circumstance which gave rise to the well-known joke of Stilo Præconinus,2906 who naively enquired, what he would have done if Scipio had been the person slain?

The late Emperor Augustus was in the habit, at first, of using the figure of a Sphinx2907 for his signet; having found two of them, among the jewels of his mother, that were perfectly alike. During the Civil Wars, his friends used to employ one of these signets, in his absence, for sealing such letters and edicts as the circumstances of the times required to be issued in his name; it being far from an unmeaning pleasantry on the part of those who received these missives, that the Sphinx always brought its enigmas2908 with it. The frog, too, on the seal of Mæcenas, was held in great terror, by reason of the monetary imposts which it announced. At a later period, with the view of avoiding the sarcasms relative to the Sphinx, Augustus made use of a signet with a figure upon it of Alexander the Great.