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Browne pointed out in his work on "Vulgar Errors" (1646) that 

 " Diamonds are so far from breaking hammers, that they sub- 

 mit to pistillation and resist not an ordinary pestle." They can, 

 in fact, be reduced to powder in a steel mortar. This, however, 

 is due to no lack of hardness. A very striking experiment was 

 performed by Sir William Crookes at the B.A. meeting at 

 Kimberley, September 5, 1905. I quote his description: " On the 

 flattened apex of a conical block of steel I place a diamond and 

 upon it I bring down a second cone of steel. With the lamp I 

 project an image of the diamond and steel faces on the screen, and 

 force them together by hydraulic power. I can squeeze the stone 

 into the steel blocks without injuring it in the slightest degree." 

 In doing this Sir William applied a pressure of 170 tons per square 

 inch to the diamond. W T e now return to the cutting of the stones. 

 The rough diamond in its natural state is first submitted to a most 

 careful examination so that not only may its purity of colour be 

 estimated, but also that any flaws or specks it may contain shall 

 be detected. If any of these occur at or near the centre of the 

 stone it will be necessary to make two or more approximately 

 equal cut stones from the original, but in most cases it will be 

 possible to make one chief stone. One or more of the split-off 

 portions may be large enough to cut and polish as small diamonds 

 or, in any case, they can be used for diamond dust. These points 

 being settled, the diamond is inserted into a cement of brickdust 

 and resin, made soft by heat, and contained in a ferrule projecting 

 from one end of a wooden cylinder. When the cement is quite 

 cold the operator takes another diamond having a sharp edge and 

 cuts with it a scratch or notch in the one that is to be cleaved. 

 When the notch is deep enough the wooden cylinder is fixed in 

 a block of lead. Into the notch is inserted the blunt edge of a 

 small steel blade, a quick "sharp blow is struck on the blade and 

 the stone is split. It is now taken out of the cement and put back 

 again in the proper position for the next split and so on until the 

 stone is of the general shape decided upon. From the cleaver the 

 diamond goes to the cutter. He grinds two stones together until 

 both are quite smooth, and thus further developes the facets pro- 

 duced in the rough by the cleaver or splitter. The third and last 

 stage is that of polishing. This is done by means of diamond 

 dust moistened with oil on horizontal wheels making about 2,000 

 revolutions a minute. In this, as in the other two operations, w T e 

 have a good example of the extraordinary delicacy and accuracy 

 of which skilled human labour is capable. Amsterdam has long 

 been the chief seat of the industry, but it is also carried on in 

 London, Paris, and other places. During all the processes the 

 greatest care is taken that the precious dust shall not be lost. 

 Diamonds are cut in various forms, among which the " brilliant " 

 is the chief. The word is often used alone to indicate a diamond, 

 but strictly it is a form to which other stones than the diamond 

 may be brought. The typical brilliant has 58 polished facets. 33 

 of these, including the large central " table," are in the " crown " 



