GEMS, NATURAL AND ARTIFICIAL 



is singly refractive. If the two colors are different, it 

 is doubly refractive. The determination of this fact 

 is of great importance in identifying a gem. 



THE CUTTING OF PRECIOUS STONES 



Scientific gem-cutting the knowledge of how to grind 

 the facets so as to bring out the greatest amount of 

 brilliancy is a comparatively recent art. Gem stones, 

 as we know, have been used for ornaments, amulets, 

 or in connection with religious rites, since the begin- 

 ning of history; but in ancient times they were worn 

 either in the natural state, or cut in a crude manner 

 without regard to the arrangement of the refracting 

 surfaces. During the latter part of the fifteenth cen- 

 tury, however, some time between the years 1460 and 

 1480, a gem-cutter of Bruges named Van Berquen 

 discovered that by a certain arrangement of the facets 

 on a diamond the reflection and dispersion of light 

 were greatly increased. The fame of this gem-cutter 

 spread quickly, and many valuable gems found their 

 way into his establishment to be cut. Bruges became 

 the center of the industry and for a time had the mon- 

 opoly of the industry; but after the death of Van Ber- 

 quen the craftsmen of the guild scattered to other cities, 

 so that Amsterdam, Antwerp, and Paris divided the 

 trade. Amsterdam and Antwerp still monopolize 

 most of the fine work, although France, England, and 

 even the United States in recent years, have had large 

 gem-cutting establishments. The same methods are 

 employed in all these places, and, curiously enough, 

 VOL. rx.~ 20 [ 305 ] 



