The Transitional Period proper, from 500 B.C. to 450 B.C., produced very fine gems with genre subjects. These were probably influenced somewhat by the freedom acquired by the Greek vase-painters, whose art reached its perfection in that era. From thence onward no subject seems to have daunted the gem-engraver who reproduced the most intricate details and reduced to miniature marvelously well the beauties of those groups of colossal statuary that particularly inspired him, subjects from paintings or his own devices, or figures, heads and portraits of his contemporaries, men, women and children--portraits which must have been possessed of the virtue of likenesses to an extraordinary degree, else they would not for centuries have continued in such favor. As Renton says, “we are forcefully reminded of the extreme durability of engraved gems when we reflect that some at the present time contained in our museums and collections have been buried in tombs or in the earth; others have been thrown upon the shore, washed by the sea or exposed to fire, pillage, and other dangers, but still appearing with the engraving in some instances as clear, sharp, and defined as it was the day they left the artist’s hands.” It is this careful and peculiar finish to the work that distinguishes the truly antique gems from the spurious. We have little reliable data concerning the artists in glyptic art from the primitive period represented by the Samian Theodorus, who made the famous ring for Polycrates, to the period of the art’s perfection, 450 B.C. to around 400 B.C. To the latter period belongs, by right of his excellence, Pyrgoteles, who engraved the seals of Alexander. The least doubtful names, perhaps, are those of Agathopous, Apollonides, Aspasios, Athēniōn, Boēthos, Dexamenos, Dioskouridēs, Epitynchanos, Hērakleides, Hērophilos, Hyllos, Mykon, Nikandrus, Onēsus, Pamphilos, Prōtarchos, Solōn, and Teukrus, tedious to catalogue perhaps, still a small number out of proportion to the vast quantity of intaglii that have been recovered from the past. We are sure of Dioskourides under Augustus, but even in antiquity names were forged upon gems at a later date or by an alien hand, such forgeries being especially common from the time of the Renaissance on. Indeed, it became quite as much the fashion to mutilate antique gems by adding bogus signatures as it did later to imitate the glyptic art of the ancients and attempt to pawn off forgeries and fabrications on the enthusiastic but indiscriminating. Of this the reader will find further mention in the chapter on Fraudulent Art, which follows. In ancient times intaglii were also imitated in glass and much affected by the poorer classes, so early had the idea of cheap imitation jewelry taken root.