GEMS, NATURAL AND ARTIFICIAL 



held by means of iron clamps against the surface of 

 the skeif , and kept in position by heavy weights. Four 

 of these clamps are manipulated by each operator 

 at the same time, and he is able to examine first one 

 diamond and then another, occasionally plunging 

 each into cold water to prevent the heat generated by 

 the friction unsoldering the stone, which would occa- 

 sion considerable damage to the gem and loss of val- 

 uable time and labor. 



"The surface of the skeif derives its erosive prop- 

 erty from the continual application of diamond dust 

 mixed with olive oil, and to the dust which comes off 

 the stones undergoing the process. The facets are 

 polished on to the diamond by means of pressure 

 against this erosive surface, while it revolves at a high 

 speed." 



It is usual to cut the diamond into one of three 

 forms, the "brilliant," "rose," or "briolette." The 

 brilliant form is the one into which most valuable 

 gems are cut. The front of a brilliant has an octagonal 

 surface in the center, known as the "table," which 

 is surrounded by thirty-two facets extending to the 

 edge of the stone. The back is pyramidal, having 

 twenty-four facets, reaching from the edge, or "girdle" 

 of the stone to the apex of the pyramid, on which a 

 small facet, the "culet," is cut, parallel with the table. 



The "brilliant" is well named, for the maximum 

 brilliancy is developed by this form of cutting. If the 

 cutting is perfect, every ray of light entering the upper 

 surface of the gem is refracted within the stone and out 

 again from the same surface. 



[309] 



