Gem

(jěm.) [From L. gemma, a precious stone.] (Fine Arts.) Generally, precious stones, or such as are employed in jewelry, more especially those which by their color, brilliancy, polish, purity, and rarity, are sought after and prized as objects of ornament. G. of the most valuable kinds form the principal part of the crown-jewels of sovereign houses, and are esteemed not merely for their beauty, but as comprising the greatest value in the smallest bulk. G. are remarkable for their hardne and lustre, and those usually employed are diamonds, rubies, sapphires, emeralds, topazes, hyacinths, and chrysoberyls, which are the most valuable; crystalline quartz, pellucid, opalescent, or of various hues; amethyst, lapis lazuli, malachite, jasper, agate, chalcedony, onyx, carnelian, and bloodstone. They are of various cla es, and proportional values, and are elsewhere described in this work under their proper heads.ARTIFICIAL G. have become, in recent times, largely and succe fully fabricated by crystallizing mixtures containing their component parts at a very high temp. Artificial rubies, opals, emeralds, garnets, & c., have thus been produced, and so as to closely resemble the real stones in regard to color, form, and hardne . The diamond yet remains to be imitated succe fully by art. GEM-ENGRAVING, or SCULPTURE (litho glyptics), is an art of high antiquity, and consists in representing designs upon precious stones, either in raised work, as cameos, or by figures cut below the surface, as intaglios. This art flourished among the Greeks to perfection, and it was also practised by the Babylonians, Egyptians, and Hebrews. It afterward sunk into decadence, until the 15th cent., when it was revived in Italy: it has, in more modern times, reached to a high state of perfection and beauty. [s. 399]