2o8 



THE POPULAR SCIENCE MONTHLY. 



of the gem, and form table diamonds by adroitly striking along one 

 of the planes with a shai'p-edged tool, thereby separating the layers, 

 as slate is rifted by the miner. This oj^eration, which apj^ears so 

 simple, really requires considerable skill, and much of that acquired 

 instinct or tact which is best exhibited by our Western Indians, who 

 chip, with marvelous rapidity and certainty, a glass-bottle into sym- 

 metrical arrow-heads. 



The workman at a glance ascertains the direction of the laminae, 

 and with another diamond cuts a notch at the point where he would 

 begin operations. In this notch he places the edge of his blunt steel 

 knife, and, by tapping the back of it with a light iron rod, he splits 

 the diamond with perfect ease. In reducing the natural diamond to 

 a regular form, much of its substance is lost, and sometimes as much 

 as one-half the weight of the stone. The amount of loss, however, de- 



FiG. 5.- 



-The Koh-i-noor after Eecxjtting. 

 Weight, 102^ carats. 



Fig. 6. The Regent. 

 carats. 



Weight, 136 



pends greatly on the natural form of the crystal. Perfect octahe- 

 drons lose but one-fifth of their weight when fashioned into brilliants, 

 but rhombohedrons lose over one-third on taking the same form. The 

 following figures will give some notion of the loss : 



The Mogul weighed in the rough VSOJ carats. 



Reduced in cutting to 279VV " 



The Regent weighed 410 carats ; reduced to 136|f " 



The Koh-i-noor weighed 186 J carats; reduced to 102i " 



The Star of the South weighed 254i carats ; reduced to . . 124^\ " 



The process of cutting diamonds of large size is always attended 

 with risk, and is necessarily a costly operation. The Regent cost for 

 cutting $25,000, and occupied two yeai-s' time. The Star of the South 

 occupied only ninety days, and the Koh-i-noor only thirty-eight work- 

 ing-days. This great feat in diamond-cutting was performed by the 



