The names of the artists who engraved the gems, and of the proprietors, are occasionally found upon them. After the Antonines, indeed, the art rapidly declined, and portraits after Sev erus are rare, although even that of Mauricius is said to occur. At the middle period of the Em pire, the work is exceedingly rude, often merely scratched out by a diamond point in earnelians, jaspers, and garnets. The gems of this latter period are sometimes square, generally, however, the long or convex oval. The camel, or gems 'in relief, the ancient cctypa sculpture, appear prominently at the period of the Roman Empire. This term camel; of uncertain origin, is applied to engravings on stone of two or more layers. such as the onyx or sardonyx, and niccolo, and is differ ent from the relief gems cut out of stones of one color. Ancient camel, indeed, are of the greatest rarity. The smaller ones were used for rings; the larger, which are often perforated, are sup posed to have been often attached to the dress as phalerce. They were worked out with the dia mond point. Cameos are not supposed to be earlier than the Alexandrian period (c. 200 n.c.), though some carnelian scarahoids of Archaic Greek times, like several in the British Museum, are small premonitory specimens of what was to be developed into the most gorgeous branch of gem-carving, whose brilliant coloring and large size hardly accorded with the Hellenic simplicity of the Golden Age. The first great cameos are those of the Ptolemies, such as the great Naples cameo of Zeus by Sosus, that of Ptolemy and Arsinoe in the Hermitage of Saint Petersburg, the onyx cap of Ptolemy at the Cabinet des //Waffles in Paris, the famous Farnese cup, the vase of Saint Martin d'Agaune—all master pieces, and serving as models for the artists of the Augustan age. To the early Roman Empire belong some superb pieces, such as the "Triumph of Augustus," a sardonyx in the Vienna collec tion, and the so-called "Apotheosis of Augustus" in the Bibliot4que Nationale in Paris, also a sardonyx. The composition in these Roman works is elaborate, and the figures numerous and some times in several rows. On the Vienna sardonyx Jupiter, Augustus, and Roma are enthroned above, in the middle row are Terra, Ocean, Abun dance, Germanicus, Victory, and a triumphal char iot, while below are German and other captives. The cameo at Saint Petersburg is one foot long, and that in the Marlborough Collection, with the heads of Didius, Julianus, and Mantio Scantilla, is eight and one-half inches long by six inches high. Still larger carvings are in the form of vases, cups, boxes. These gems were principally worn as objects of attire, and Heliogabalus is even said to have placed intaglio in his shoes. The names of artists are rarely found upon camei; a cele brated one of the Marlborough Collection, indeed, has the name of Tryphon, but there is consider able doubt about the authenticity of the inscrip tion.
The subjects of classic gems embrace the whole circle of ancient art, and follow the laws of its development, animal forms being by those of deities and subjects derived from the bat tles of Greeks and Amazons and centaurs, the exploits of Hercules and other heroes; then by scenes from tragedians and later myths; and finally by portraits, historical representations, and allegories. The inscriptions consist of the names of artists, sometimes in the genitive case, but often accompanied with the verb irotei, made; addresses to individuals; gnomic or other agyings, indicating that the gems are amulets against demons, thieves, and various evils; or charms for procuring love; the names of the possessors, and sometimes addresses, occasional ly even distichs of poetry, and various mottoes. These inscriptions were often, added by subse quent possessors, and are not of the age of the gem itself. The number of artists, although very considerable, does not exceed 100 authentic names. The number of false antique stones pro duced by eminent engravers since the revival of the arts has rendered the diagnosis of gems so difficult that no branch of archxology requires greater judgment. All gems of high artistic merit and great finish are suspected, especially those with groups of many figures, regular edges, and polished faces, or too great a polish in the deep parts. Coarser imitations have been produced by backing pastes or colored glass (see GEMS, IMITATION) with stones, and mounting them in rings so as to pass for gems. The appearance
of wear and friction has been produced by intro ducing them for a while into the gizzards of tur keys, or in pierced boxes plunged in the beds of rivers. The judgment upon gems can be matured, however, only by a careful study and familiarity with all branches of ancient art. The coarser imi tations of pastes, the tongue, the file, and the graver will detect; but old gems reengraved, or new compositions invented, require the most care ful survey. The place or circumstances of discov ery are no guarantee against deception, the com merce in false antiques being successfully plied upon the unwary even in the far East.
The chief implement used by the ancient en gravers appears to have been made by splitting diamonds into splints by a heavy hammer, and then fixing these points like glaziers' diamonds into iron instruments, with which the work was executed by the hand. The drill was also exten sively used for hollowing out the deeper and larger parts of the work, before the diamond point was brought into operation, and finally, emery powder was used for polishing. The wheel, a minute disk of copper, secured to the end of a spindle, and moistened with olive oil, emery powder, or diamond-dust, and driven by a lathe, does not appear to have come into use till the Byzantine epoch. It has been conjectured that the artist used lenses of some kind, or globes filled with water, to execute his minute work; but the ancient, like the modern engraver, rather felt than saw his way. A more primitive method was that in which nothing but a copper tool was used, moistened as described. A still more primi tive technique is that of many rude, early, or provincial Babylonian cylinders and proto-Hel lenic 'Island stones' where the drill is the only instrument, and the forms are indicated either by larger or smaller hollows connected usually by straight lines. All these processes were not em ployed by the same artist, for besides the en graver (sculptor cavarius, dactyliographus), there was a polisher (politor), not to mention arrangers (compositores gemmarum), and mer chants (gemmarii, mangones gentmarum).
The decadence in sculpture was very quickly felt in gem-cutting, which produced little and that of hardly any value, after the second cen tury A.D. Even the small skill shown in Gnostic and Early Christian examples was lost, and the Merovingian and Carolingian monarchs, except in the case of monograms engraved on signet rings, were obliged to use antique gems, instead of those engraved by the artists of their day. Rock-crystals, however, were employed in a By zantine style of art, with sacred subjects, in the ninth century; and a few other examples have been preserved in the Treasury of Saint Mark's at Venice, and in Paris (BibliothMue Nationale). The art was all but lost in the West, except for a few pieces such as the Gothic rings of the Guerrazar treasury, the seal of Lothair at Aix la-Chapelle, and the Crucifix of Conques. It was revived in the time of Lorenzo de' Medici, when Giovanni delle Corniole, at Florence, and Domen ico dei Camei, at Milan, worked under his pa tronage. A subsequent school of gem-engravers originated with Pietro Maria da Pescia, who worked for Leo X.; the chief representatives of the school are Micheline, Matted de' Benedetti, the celebrated painters Francia, M. A. Moretti, Caradossa of Milan, Leonardo da Vinci, J. Ta gliacarne. Giovanni Bernardi of Castel Bolognese, celebrated for a Tityus copied from Michelangelo. These were succeeded by Matted del Nassaro of Verona, who worked for Francis I., and produced a crucifixion on heliotrope, so that the red spots seemed drops of blood issuing from the wounds of Christ; Caraglio, who flourished in Poland about 1570; Valerio dei Belli, who chiefly employed rock-crystal ; Marmite, Domenico di Polo, Nonni, Anichini of Ferrara, and Alessandro Cesari, cele brated for a cameo head of Phocion; Dei Rossi, a Milanese, who engraved the largest cameo of modern times; Giacomo da Trezzo, celebrated for his portrait, who is said to have been the first to engrave on the diamond (in 1564), an honor disputed, however, by Birago, another Milanese, who made a portrait of Don Carlos and the arms of Spain on this gem.