two or more layers, such as the onyx or sardonyx, and niecolo, and is different from the relief-gems cut out of stones of one color. Ancient camel, indeed, are of the great est rariety, and are not older than the imperial days of Rome. The smaller ones were used for rings; the larger, which are often perforated, are supposed to have been worn in the armor or dress, phalerce. They were worked out with the diamond point; chiseled, so to say, out of the stone; and have, when examined, a rough appearance. The most remarkable ancient• camie known are those of the Vienna collection, supposed to represent the apotheosis of Augustus, on which are Augustus, Jupiter, and Borne enthroned, the Earth, Ocean, Abundance, Germanicus, Victory, a triumphal car, Tibe rius, and German captives; another, in the Same collection, with Ptolemy II. and Arsi noe, the great cameo in the Bibliotheque at Paris, representing the.apotheesis of Augus tus; another to the collection of the Netherlands; and a fourth in the Vatican; a cameo at St. Petersburgh, one foot long, and another, eight and a half inches wide by six inches high, in the Marlborough collection, with the heads of Didius, Julian and Man ila Scant]lla. At a later period, the art lied considerably declined, and the Christians of the later days of the empire were content with 'engraving inscriptions on camel. These gems were principally worn as objects of attire, and Aeliogabulus is said to have placed even intagli in his shoes. The names of artists are rarely found upon camel; a celebrated one of the Marlborough collection, indeed, has the name of Tryphon, but there is considerable doubt about the authenticity of the inscription.
The subjects of ancient gems embrace the whole cifcle of ancient art, and follow the laws of its development, animal forms being succeeded by those of deities and subjects derived from the battles of Greeks and Amazons and Centaurs, the exploits of Hercu les, 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 deities, heroes,• and subjects; dedications to deities; the . names of artists, sometimes in the genitive case, but often accompanied with the verb epoei, mak ing" (he affected imperfect use after the time of Alexander the great); addresses to individuals; gnomic or other sayings, indicating that the gems are amulets.amainst demons, thieves, and various evils; or charms for procuring love; the names of the possessors, and sometimes addresses, occasionally even distiehs of poetry, and various mottoes. These inscriptions were often added by subsequent possessors, and are not of the age of the gem itself. The number of artists, although very considerable, does not exceed 100 authentic names; and the true names are supposed to be distinguished front false ones by being placed at the side of the composition in very small letters terminating in dots; but even these have been successfully imitated by modern artists, and the great est criticism and learning .have been displayed to detect real ancient names by their orthography and palmography. The number of false antique stones produced by emi nent engravers since the revival of the arts, has rendered the diagnosis of gems so diffi cult, that, no branch of archmology requires greater judgment. All gems of high artis tic 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 imi tations have been produced pastes or colored glass (see GEMS, IMITATION) with stones, and mounting them in rings, so as too pass for a gem. The appearance of
wear and friction has been produced by introducing, them for awhile into the gizzards of turkeys, or in pierced boxes plunged in the beds of rivers. The judgment upon gems can be, however, only matured by a careful study and familiarity with all branches of ancient att. The coarser imitations of pastes, the tongue, the file, and the graver will detect; but old gems re-engraved, or new compositions invented, require the most careful survey. The place or circumstance of discovery is only a feeble guarantee against deception, the commerce in false antiques being successfully plied upon the unwary even in the far east.
The chief implement used by the ancient engravers appears to have been made by splitting diamonds into splints (adamanfis erustm) by a heavy hammer,and then fixing these points like glaziers' diamonds into iron instruments, with which the work was executed by the hand (feria retusa). The drill, terebra, was also extensively used for hollowing out the deeper and larger parts of the and emery powder, the samaris or Naxian Stone, for polishing. The so-called wheel, a minute disk of copper, secured to the end of a spindle, and moistened with 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 conjec tured 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. All these processes were not employed by the same artist, for besides the engraver (sealptor eararius, claetyliographns), there was a polisher (politor), not to mention arrang ers (e,ompos-itores gemmarum), and merchants (qemmarii, mangones gemmorum) who drove a flourishing trade in emeralds and pearls and engraved stones in the days of lIorace.
The general fall of the arts at the period of the Byzantine empire, seems to have been accompanied by the decline Of the art of engraving on gems; and the Merovingian and Carlovingian monarchs were obliged to use antique gems, instead of those engraved by the artists of their day. Rock-crystuls, however, were engaged in a Byzantine style of art, with sacred subjects, in the 0th c.; but the art was all but lost till the rise of Lorenzo de Medici, when Giovanni delle Corniole, at Florence, and Domenico dei Camel, at Milan, worked under his patronage. A subsequent school of gem-engravers originated with Pietro Maria de Pescia, who worked for Leo X.; the chief representa tives of the school arc Michelin°, Matteo de Benedetti, the celebrated painters Francia, M. A. Moretti, Caradosso of Milan, Severo of Bavenna, Leonardb da Vinci, J. Taglia carne, Bernardi of Castel Bolognese, who died 1555, celebrated for a Tityus copied from M. Angelo. These were succeeded by Matteo 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 in 1569; Valcrio dci Belli, who chiefly employed rock-crystal; Marmite, Domenico di Polo, Nanni, Anichini of Ferrara, and Alessandro Cesari, celebrated for a cameo head of Phocion; Dci Rossi, a Milanese, engraved the largest cameo of modern times; Jacomo da Trezzo, celebrated for his portrait, is said to have been the first to engrave on the diamond in 1564—an honor disputed, however, by Birago, another Milanese, both artists having been in the service of Philip II. of Spain, who made a portrait of Don Carlos and the arms of Spain on this gem.