DIAMONDS AND DIAMOND CUTTING. 197 



light refractor, is pure carbon, like the diamond, 

 but it is not perfectly, crystalline. It is semi-amor- 

 phous in structure ; and if it was not used for its 

 mechanical value, it would be as worthless as a bit 

 of charcoal. It is now worth in the market about 

 six dollars a pennyweight. 



When two diamonds are rubbed together they 

 are mutually abraded or worn away, and hence if 

 we have a valuable one which we wish to cut, to 

 develop its brilliancy, we have only to select another 

 which by its shape is worthless, and bring this to 

 bear mechanically upon the other, and the work 

 goes on. The worthless diamond may be called 

 the tool with which the cutter elaborates the valued 

 gem. Each is placed in cement, conically heaped 

 at one end of two sticks of convenient handling size. 

 The cutter is so placed in soft cement that its cut- 

 ting angle can be employed to the best advantage 

 upon the clear stone, which is similarly adjusted 

 to present the surface to be abraded. After the 

 cement has hardened, the workman grasps the stick, 

 holding the cutting diamond in his right hand and 

 that with the gem in his left, and the stones are 

 brought together over a double metallic box, the 

 "inner section of which is provided with a perforated 

 bottom, being half the depth of the outer, into 

 which it closely fits. The particles which become 

 detached from both stones fall into the inner box, 



