Most persons have occasionally handled specimens of the precious stones or “gems;” but few of them, perhaps, are aware that our pebbles of the road-side and sea-shore claim a common origin with these dazzling crystals. Such is, however, the fact. Chemical analysis, availing itself of the blow-pipe, the solvent acids, and the voltaic battery, has succeeded in determining the base of every known gem. And the earths which furnish such bases are chiefly two—ALUMINA, or clay, and SILICA, or pure flint. From these, with an admixture of lime, and sometimes of iron, in small quantities, all the native gems are derived, with the exception of the diamond, whose base is CARBON. Intensely hard as these substances are, and apparently not susceptible of change if left to themselves, they have probably passed through great chemical changes in the silent laboratory of Nature. For it is supposed that our operations in analysis, if carefully conducted, merely bring back their subjects, by a kind of _reversing_ process, to their several primitive bases. Now it is evident that the commoner pebbles are derived from these same earths, of clay or flint, albeit in a debased condition. For there is nothing else of which they could be made: neither do they exhibit any properties foreign to those which such substances possess. Yet, how vast is the difference between an oriental gem and the brightest production of clay-pits or granite rocks. Not greater, however, than that between Damascus steel and coarse pig-iron; or, between French lawn and sail-cloth. And if Art can work such distinctions, why not Nature? In fact, a perfect gem is a master-piece which chemistry and crystallization have combined to elaborate, and which man has ransacked the corners of the earth to obtain. The deep has been made to surrender its treasures to the diver or the sunken net: the rock has been blasted, and its inmost vein searched: the rushing river filtered, and its sand sifted: and the contents of the jeweller’s caskets are the result. Here may be seen diamonds from Golconda; and rubies from Samarcand and Pegu: sapphires, emeralds, and amethysts from Persia, Arabia, and Armenia: the topaz, blazing like fire, from the Indies or from the Ural: the turquoise, with its delicious blue, from Arabia and Palestine: the opal from Honduras: the blood-red garnet and amandine from Bohemia, Ceylon, and Greenland: the jacinth and the chrysoprase, the chrysolite and beryl, with pure pearls of globular form, all from the land of the rising sun, while a deep brown jasper, rayed with stripes and rings as black as jet, has travelled like a wandering palmer from sultry Egypt or the terrible desert of Sinai.