Artificial Rubles

In a recent lecture Prof. A. P. Brown of Philadelphia described the methods now praeticed for making artificial gems. Although minute diamonds can be made, with the aid of the electric furnace, none large enough to be employed in jewelry have yet been produced. But rubies of large size, and as fine in color and aupearance as the best natural gems, have been made. The ruby is composed of oxide of aluminium. A certain method of detecting artificial rubies is by examination witti a microscope. The natural gem is always filled with minute cracks, invisible to the naked eye, but perfectly discernible with a high magnifying power. The artificial ruby has no cracks, but, on the other hand, is filled with minute bubbles, or gas-holes. Thls test, according to Professor Brown, is the only one by which the best artificial rubies can be distinguished from the same gems as nature makes them.-