August 1, 1864.] THE TECHNOLOGIST. 



WHAT PRECIOUS STONES ARE JIADE^OF. 39 



stone a diamond, as too many have found to their coet. Yet these pre- 

 cious stones are now apparently as common as garnets or cornelians. 

 They may be seen sparkling upon the unwashed fingers of some sturdy 

 Bridget, or blazing upon tlie breast of Patrick, attired for a holiday 

 stroll. The shop boys and girls have them, and it seems almost as if 

 some benevolent society had been formed for the purpose of" supplying 

 every man with his own diamond." 



Let not the reader with exclusive tastes, who is, perhaps, the possessor 

 of a genuine stone, mourn over this parade. In the days when his jewel 

 shall gleam untarnished and with renewed splendour, Patrick's shall 

 fade away into a dull gleam. The spirit of his " stone" shall depart, 

 and humbled, robbed of its glitter, the light plucked out, and the flame 

 with whieh it once glowed quenched for ever ; it shall be cast aside as 

 useless, and be without its place among men. 



" Gew-gaws" correctly express the value which attaches to these paste 

 imitations of the pi*ecious diamond — a stone which is the first among 

 jewels, which has never been deposed, and it is safe to say never will 

 be, whose fire rages within, and increases until the eye is dazzled almost 

 beyond endurance ; whose gleam is hard, cold, and unsubdued. It 

 fairly revels in its vicious glitter and seems to send out rays that pierce 

 like the arrows shot from Diana's bow. Old as it is, its value is always 

 great, and at the present time beyond the reach of persons of ordinary 

 means. It is in some countries a standard of value, like gold, and it is 

 said that persons in the United States are now purchasing them as 

 investments which cannot depreciate or lose, except in the interest. 



The paste imitations of the diamond are known by different titles ; 

 sometimes as the " California diamond," " Australian pebble diamond," 

 &c. ; but the basis of all of them is quartz or rock-crystal, pulverized 

 and fused in combination with the oxides of certain metals. The paste 

 is technically known as strass, after the discoverer, Strass, of Strasburgh, 

 who, by a series of experiments in the seventeenth century, was very 

 successful in making imitations of precious stones. Strass is composed 

 of silex, potash, borax, red lead, and sometimes arsenic, in the following 

 proportions : 300 parts silex (quartz, flint, or pure sand) ; 96 parts of 

 potash ; 27 parts of borax (prepared from the boracic acid) ; 514 parts of 

 white lead ; 1 part of arsenic. This mixture is put into a covered 

 Hessian crucible and kept at a great heat in a pottery furnace for 

 twenty-four hours. The longer the mass is kept, the clearer it will 

 be when turned out. 



Strass of this kind is used for imitating the diamond, rock crystal, 

 and white topaz. There are many signs, however, by which this strass, 

 or Californian diamond, can be detected by the experienced eye. 

 These signs are its inferior specific gravity, its want of hardness, and 

 the absence of coldness to the tongue-test, or when it is applied to that 

 organ. Good strass is so hard that fire flies when it is rubbed on a tile, 

 but it is readily attacked by fine quartz-sand on a grinding plate. The 



