Diamonds and precious stones, a popular account of gems .. . Enamel. and the latter in his treatise on the Essence ofMinerals^ states explicitly that there were menwho fabricated artificial jewels. Among the pre-cious stones counterfeited, he instances the hya-cinth, sapphire, emerald, ruby, and topaz. At the commencement of the Renaissance thefabrication of false stones still continued ; but it wasnot yet separated from much hesitation and experi-ment. Cardan proves this in his curious receipts. A century later we perceive by the descriptions FALSE PRECIOUS STONES. 243 of Kircher that the ind
Diamonds and precious stones, a popular account of gems .. . Enamel. and the latter in his treatise on the Essence ofMinerals^ states explicitly that there were menwho fabricated artificial jewels. Among the pre-cious stones counterfeited, he instances the hya-cinth, sapphire, emerald, ruby, and topaz. At the commencement of the Renaissance thefabrication of false stones still continued ; but it wasnot yet separated from much hesitation and experi-ment. Cardan proves this in his curious receipts. A century later we perceive by the descriptions FALSE PRECIOUS STONES. 243 of Kircher that the industry had greatly the unburned brick of Cardan, in whose cavityhis mixture for precious stones was heated, excel-lent crucibles had succeeded ; special furnaces hadreplaced the brick-kiln ; and in the time of Kircher,that is to say, about the middle of the seventeenthcentury, false stones were no longer manufacturedaccording to methods differing for each stone, butaccording to a general formula much the same asthat followed at the present Fig. 96.—Eg^ptian Moulding in Ceramic Paste. No other proof is needed than the writings ofKircher to dissipate the error that has ascribed theinvention of strass—a peculiar kind of glass of con-siderable refractive power, which forms the base ofall modern artificial gems—to a workman of thatname, towards the close of the last century. Thisproduction was perfectly well known in the middleages ; and it was used for exactly the same purposesas it is used for to-day—for decoration, and thecounterfeiting of precious stones. It is distin-guished from ordinary glass by the presence of 244 PRECIOUS STONES. about 50 per cent, of oxide of lead among its con-stituents. There existed in the middle ages, and probablyhad existed among the ancients also, a substancecalled at first amasa, then encatista, and lastlysmalta, from which last term our modern émail(enamel) is derived. These were generic expres-sions for substances formed
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectgems, booksubjectprec
