SAPPHIRE has been selected as one of the three general examples of lapidary work, described in this catalogue, namely Alabaster in explanation of the mode of working the softest stones, and other allied substances, Carnelian in explanation of the modes pursued with stones of greater hardness than Alabaster, but inferior in this respect to Sapphire, the subject of the present article. Sapphires are alone exceeded in hardness by the diamond, which last is pre-eminent over all natural substances, in point of hardness.

The previous articles on Alabaster and Carnelian may with advantage be here referred to, as containing much general information upon the lapidary art, and which will be more fully described in the 34th Chapter of this volume; but it should be here observed that the harder and smaller the gems to be wrought, the harder are the metallic laps or mills respectively employed by the lapidary, and although sapphire may in truth be entirely wrought by the method employed for carnelian, the present will be found the more usual, as well as the more economical practice. As gems are usually retained of as great size as their irregularities of surface will admit, sapphires and many other gems are seldom reduced in size except by grinding, or as it is more commonly called, by cutting them. When however they are divided it is more commonly done by cleavage or splitting, than by slitting or sawing, and which process when resorted to, is effected nearly as usual with an iron sheer fed with diamond dust, and lubricated with brick oil; the sheer for sapphires is however very much smaller than for general lapidary works, and is principally met with in the hands of watch jewellers. Secondly, the lapidary commonly grinds and cuts the facets on sapphires upon a copper lap, supplied with diamond dust and brick oil, which cuts more quickly and delicately than the lead mill with emery; and 3rdly, these gems are polished upon a copper lap with rottenstone and water, the tool being jagged after the manner more fully described under the head Carnelian. 2. - The practice of the watch jeweller in making the pivot holes for watches in ruby and sapphire, is described in the first volume of this work, pages 178 - 9: Diamond powder is used throughout, and of three degrees of fineness, the coarsest on copper tools, the medium on glass, and the finest on pewter tools for the last polish.

Phillips says the sapphire has obtained several names amongst mineralogists and jewellers, dependent on its colour and lustre, namely, - White Sapphire, when transparent or translucent. Oriental Sapphire, when blue. Oriental Amethyst, when violet blue. Oriental Topaz, when yellow. Oriental Emerald, when green. Oriental Ruby, when red.

Chatoyant, or Opalescent Sapphire with pearly reflections. Girasol Sapphire, when transparent, and with a pale reddish or pale bluish reflection.

Asteria or Star Sapphire, exhibits 6 milk-white rays, radiating from the center of an hexagonal prism, and placed at right angles to its sides. The asteria is found in both the red and blue varieties of Sapphire, and is always cut en cabochon to show the figure.

All the above Sapphires, the Chrysoberyl, occasionally the Zircon and some others of the gems, are cut with diamond powder and polished with rottenstone, as above described.