THE DIAMOND AND OTHER PRECIOUS STONES. 337 



all the other crystals, aud especially those of quartz;, are much more 

 brilliant iu their natural state. Had Socrates, who regarded the natural 

 man as a block of marble, from which art can create a beautifui statue, 

 known of the transformation created by the cutting of the rough dia- 

 mond, he would certainly have preferred this comparison. The dif- 

 ference, however, in money value between the cut and the uncut diamond 

 is not 80 great as might be supposed. For if the rough diamond loses 

 half its weight by cutting, on the other hand, its value is doubled by 

 the operation, without estimating the dust remaining, which has a 

 value in the arts from its being employed in polishing many gems as 

 well as the diamond itself. 



The ancients do not appear to have had a suspicion that the diamond 

 could be cut. They only knew it in its natural condition as a stone, 

 having eight triangular surfaces, and in every direction presenting a 

 double pyramid. 



Louis de Berqueu, an artist of Bruges, about the middle of the fifteenth 

 century, conceived the idea of cutting it at first by rubbing two diamonds, 

 one against the other. If, in fact, we cement two diamonds on wooden 

 handles, and rub point against point, we shall, little by little, grind them 

 away, and obtain an artificial unpolished surface. To polish this surface 

 we must use a circular plate of steel or of cast iron, like a grindstone, 

 placed horizontally. But it is easy to see that if a diamond is merely 

 placed against this grindstone, it would require a century to produce a 

 polished surface. All that can be obtained by this process are grooves 

 cut in the iron or steel. To effect the desired object, a happy thought 

 suggested itself to Berqueu to sprinkle the surface, against which the 

 diamond was rubbed, with diamond dust mixed with oil. The surface 

 obtained in this way is regular, smooth, and perfectly polished. After 

 the discovery that facets could be produced in the diamond, experience 

 indicated in each case how a particular stone should be cut to produce 

 the most advantageous eff'ect. 



There are two principal styles of cutting. The first is called the 

 brilliant. In order to produce this style, the diamond to be cut must be 

 pointed. If not naturally in this form, it must be reduced to it artificially. 

 The points on the upper surface are ground down a little more than one- 

 half, an;! those on the lower or under surface one-eighth. Then the light, 

 entering through the larger upper surfaces, strikes the bottom surfaces, 

 is reflected backward, traverses the side facets, is refracted, and produces 

 prismatic effects. Every one knows what is the result when white light 

 is decomposed into the colors of the rainbow, and coming to the eye, 

 with every variety of hue, i:»roduces what is called the luster of the 

 diamond. For this effect the light should not be voluminous, for there 

 might be neutralization of these colors, and white light be reproduced. 

 Nor should the facets be too large, for then the eye would receive all 

 these colors at once, which would also reproduce white light. 



The large diamonds, the Eegent, belonging to the crown of France, 

 22 S 



