gems, engraved gems, agate, chalcedony, quartz, cameos, itaglios, turquoise, sard, onyx, coral, amethyst, glyptic

All who have written upon the glyptic art assume that gem engraving was completely extinct in Europe throughout the whole of the Middle Ages—that is, from the coronation of Charlemagne as Emperor of the West in the year 800 down to the middle of the fifteenth century (1453), when Greek refugees from Constantinople re-established its practice in Italy. The continuation of the art within the Greek Empire during that period does not enter into the question, for there, together with all the other arts of antiquity, it maintained a feeble existence down to the very end, as numerous cameos—some in fine sardonyx, though the greater part in bloodstone—still testify. Their agreement in style with the bezants of John I Tzimiskes and the Komnenos dynasty shows that the manufacture of such ecclesiastical decorations, whose subjects are always scriptural, was carried on with considerable activity between the tenth and thirteenth centuries. No Byzantine intaglios, however, were produced during the same period, for had such existed they would be easily recognizable by the same unmistakable stamp of the age impressed upon them, both in subject matter and treatment, that characterizes Byzantine cameos and ivory carvings. The reason for this extinction of intaglio engraving is obvious enough: signets cut in hard stones were no longer in demand, since the official seals used for stamping the leaden bullae authenticating public documents were, like coin dies, engraved in iron, while seals for personal use were engraved in the precious metals.