MANUFACTURED STONES The initial step in the examination of a crystallized substance is to determine its physical characters and to resolve it by chemical analysis into its component elements; the final, and by far the hardest, step is to build it up or synthetically prepare it from its constituents. Unknown to the world at large, work of the latter kind has long been going on within the walls of laboratories, and as the advance in knowledge placed in the hands of experimenters weapons more and more comparable with those wielded by nature, their efforts have been increasingly successful. So stupendous, however, are the powers of nature that the possibility of reproducing, by human agency, the treasured stones which are extracted from the earth in various parts of the globe at the cost of infinite toil and labour has always been derided by those ignorant of what had already been accomplished. Great, therefore, was the consternation and the turmoil when concrete evidence that could not be gainsaid showed that man’s restless efforts to bridle nature to his will were not in vain, and congresses of all the high-priests of jewellery were hastily convened to ban such unrighteous products, with what ultimate success remains to be seen. Crystallization may be caused in four different ways, of which the second alone has as yet yielded stones large enough to be cut— 1. By the separation of the substance from a saturated solution. In nature the solvent may not be merely hot water, or water charged with an acid, but molten rock, and the temperature and the pressure may be excessively high. 2. By the solidification of the liquefied substance upon cooling. Ice is a familiar example of this type. 3. By the sublimation of the vapour of the substance, which means the direct passage from the vapour to the solid state without traversing the usually intervening liquid state. It is usually the most difficult of attainment of the four methods; the most familiar instance is snow. 4. By the precipitation of the substance from a solution when set free by chemical action. Other things being equal, the simpler the composition the greater is the ease with which a substance may be expected to be formed; for, instead of one complex substance, two or more different substances may evolve, unless the conditions are nicely arranged. Attempts, for instance, to produce beryl might result instead in a mixture of chrysoberyl, phenakite, and quartz.