EMIGRANT DIAMONDS IN AMERICA. 



75 



common enougli a('co]ii]);iiiiiiiciit to Nolcauic action — and have been 

 profoundly altered by the liiuh temperature and the extreme hydro- 

 static pressure under which the mass must have been held. The 

 most important feature of this alteration has been the recrystalli- 

 zation of the carbon of the shale into diamond. 



This apparent explanation of the genesis of the diamond finds 

 strong support in the experiments of Moissan, who obtained arti- 

 ficial diamond by dissolving carbon in molten iron and immersing 

 the mass in cold water until a firm surface crust had formed. The 



Copyright, 1899, by George F. Kunz. 



Five Views of the Eagle Diamond (sixteen carats) ; enlarged about three diameters. 

 (Owned by Tiffany and Company.) 

 We are indebted to the courtesy of Mr. G. F. Kunz, of Tiffany and Company, for tlie illus- 

 trations of the Oregon and Eagle diamonds. 



'' chilled " mass was then removed, to allow its still molten core to 

 solidify slowly. This it does with the development of enormous 

 pressures, because the natural expansion of the iron on passing into 

 the solid condition is resisted by the strong shell of " chilled '' 

 metal. The isolation of the diamond was then accomplished by 

 dissolving the iron in acid. 



The prevailing forin of the South African diamonds is that of 

 a rounded crystal, with eight large and a nuiuber of minute faces — 

 a form called by crystallographers a modified octahedron. Their 



