Most of the gems of antiquity, whether rubies or diamonds, are cut rudely; and often, with the latter gem, the natural faces of the crystal are alone polished. Tavernier found that the native Hindoos polished the natural faces of the crystal if it was clear, and covered the flawed and the defective with facets to disguise them. And so common was this practice, that the traveller was always suspicious of the quality of the stone, whenever it was offered to him cut in this manner. The improvement with many of these diamonds is so slight, that we consider the fact to be one of the reasons why certain natural crystals, like those in the crown and clasp of Charlemagne, for instance, were left in their rough state; the advantage derived from cutting not being equal to the time and labor expended. It is true that we have no direct evidence of the cutting of the diamond in ancient times, and those that have descended to us from undoubted early Roman periods are in the shape of natural crystals; but still there is indirect testimony bearing in favor of the view. The ancient gem engravers were wont to use splinters of broken diamonds in their labors upon various kinds of gems; and they probably powdered the adamas, as well as varieties of corundum, for the purpose of polishing the hard stones. Scarcity of the mineral, rather than ignorance of its properties, may have prevented its general use. Janon de St. Laurent, in his work on engraving tools, maintains that the ancient instruments for the purpose of cutting gems were the same as the modern; and not only the wheel was used, but diamond dust was also employed in the process. There is no doubt that the wheel and other tools were in use in Asia for a long period before their adoption by the nations on the Mediterranean. So far as we know, Persia was the birthplace of gem engraving. Why are there not more examples of polished diamonds, if the process is so ancient? the reader may ask. We may in part answer this question by saying, that the process of cutting regular facets on the gems was not early known, or the custom adopted; and, the polishing being so difficult, that the lapidaries were content to polish the natural faces only. Polished crystals of diamonds of this character have descended to us from early times, and other examples are to be seen in ancient jewels. So little beauty was obtained by this polishing, that not much was gained in the vast labor required; and the native crystals were often used without any aid from the lapidary. We may see them in their rough crystalline forms in the crowns of the Gothic princes, the Iron Crown of Italy, and the ornaments of Charlemagne, besides other relics of ancient and even mediæval times.