PROCESS OF CUTTING 8 



to the required size, but the result is naturally less perfect than when a mechanical clamp 

 is used. 



When a facet is completed the dop is fixed in a new position in the clamp in such a 

 way as to ensure the second facet being correctly placed. By repeating this operation the 

 half of the stone not embedded in the alloy is faceted all over, the different positions of the 

 facets being attained by varying the inclination of the dop or holder in the clamp. Formerly 

 the position of the holder in the clamp necessary to produce any given inclination between 

 the facets was judged of by the eye ; this rough method was naturally not susceptible of 

 any great degree of accuracy, and, indeed, frequently gave results very far from what was 

 desired. More recently various appliances furnished with graduated arcs have made it 

 possible to turn the holder through any required angle, which thus ensures that the facets 

 are accurately located in the desired position. 



When the projecting portion of the stone has been faceted as far as possible, the alloy 

 must be re-fused and the stone embedded in a new position, so that a fresh portion will be 

 exposed for grinding. This will usually require to be done several times before the stone 

 has received its full number of facets, when it is finally freed from the alloy or cement and 

 cleaned. 



The completely faceted stone thus obtained is by no means ready for use as a gem. 

 Its facets are dull and rough, and when examined through a lens they will be seen to be 

 beset with scratches and pits marking the places from which the surface material has been 

 abraded by the cutting powder. To render the stone bright and shining, the roughnesses 

 and irregularities in the surface of the facets must be removed by polishing. This 

 process is not commenced until the whole of the grinding is completed. 



The process of polishing^ is precisely the same in principle as that of grinding ; 

 the same machine and apparatus are employed, but the cutting material, now known as the 

 polishing material, is softer than before. It may be of about the same hardness as that of 

 the stone to be polished or it may be softer. The stone is placed in a holder, and its rough 

 facets brought to bear one by one upon the polishing disc supplied with the polishing 

 material, which have replaced the grinding disc and grinding powder used in the previous 

 operation. The abrasive effect of the polishing disc is much less marked ; it gradually 

 obliterates the small striations and pits, which are the cause of the dull appearance of the 

 stone, and the facets become brighter and brighter. Finally, a point is reached when their 

 brilliancy is not increased by continued polishing ; this marks the maximum pohsh of 

 which the particular stone is susceptible and any further efforts are superfluous. It is 

 important that the maximum degree of polish should be imparted to every stone, otherwise 

 its full beauty will not be apparent. 



If the softer polishing powder is used for cutting instead of the grinding powder, the 

 facets will not require any final polishing, but will leave the disc in the most perfectly 

 polished condition. This is the case, as we shall see later, in the cutting of diamonds, 

 .since no harder cutting material can be found than their own powder ; the process of 

 cutting is, under these circumstances, extremely lengthy and proportionately expensive. It 

 is for this reason that stones other than diamond are cut with a grinding material of 

 greater hardness than that of their own substance. The process of cutting is much shortened 

 by this means and the roughness of the facets can be easily removed by a final polishing 

 with softer material. 



As a preliminary to the grinding and polishing of a stone an operation known as 

 rounding is performed, with the object of obtaining a first rough approximation to the 

 form the stone is finally to assume. The worker holds the stick of cement or other holder 



F 



