Democratic Sentinel, Volume 16, Number 44, Rensselaer, Jasper County, 18 November 1892 — TESTING DIAMONDS. [ARTICLE]

TESTING DIAMONDS.

Inexperienced People May Tell the Real from Imitation Gems. Ample testimony has recently appeared in scientific papers confirmatory of the fact that the hardness of diamondsis not perceptibly reduced by cutting and polishing. One correspondent of the San Francisco Call states that in his early experience he was accustomed to select a gem with smoothly glazed surface and after the atone was split in a cleavage plane inclined at a rather sharp angle to the natural face selected, this split face being ground and polished. In this way he was enabled to obtain at several points short knife edges, which gave superb results in ruling. It was soon found, however, that after ruling several thousand rather heavy lines the diamond was liable to lose its sharp cutting edge, and the experience became • so frequent that he was compelled to resort to the method now employed, that of grinding and polishing both faces to a knife edge. He has one ruling diamond prepared in this way which has been in constant use for four years, and its capacity for good work has not yet been reduced in the slightest degree. G. F. Kunz, who took part in the discussion on this subject, mentioned incidentally that there is no difficulty in even the most inexperienced person distinSuishing the real from the imitation iamond. If tho stone scratches sapphire it is without doubt a diamond, whereas putting the gem into a flame would not differentiate the diamond from the white topaz, or the white zircon, or the white sapphire, or the white tourmaline, or any other white stone that is not fusible. But the absolute and most simple test for diamonds is to draw the stone sharply over a piece of unpainted board in a dark room. Every diamond phosphoresces by friction.