Fig. 42.—Double
(Concavo-convex)
Cabochon.
In early days it was supposed that the extreme hardness of diamond precluded the possibility of fashioning it, and up to the fifteenth century all that was done was to remove the gum-like skin which disfigured the Indian stones and to polish the natural facets. The first notable advance was made in 1475, when Louis de Berquem discovered, as it is said quite by accident, that two diamonds if rubbed together ground each other. With confident courage he essayed the new art upon three large stones entrusted to him by Charles the Bold, to the entire satisfaction of his patron. The use of wheels or discs charged with diamond dust soon followed, but at first the lapidaries evinced their victory over such stubborn material by grinding diamond into divers fantastic shapes, and failed to realize how much might be done to enhance the intrinsic beauty of the stones by the means now at their disposal. The Indian lapidaries arrived at the same discovery independently, and Tavernier found, when visiting the country in 1665, a large number of diamond cutters actively employed. If the stone were perfectly clear, they contented themselves with polishing the natural facets; but if it contained flaws or specks, they covered it with numerous small facets haphazardly placed. The stone was invariably left in almost its original shape, and no effort was made to improve the symmetry.
Fig. 43.—Table Cut
(top view).
Fig. 44.—Table Cut
(side view).
For a long time little further progress was made, and even nearly a century after Berquem the only regular patterns known to Kentmann, who wrote in 1562, were the diamond-point and the diamond-table (Figs. 43–44). The former consisted of the natural octahedron facets ground to regular shape, and was long employed for the minute stones which were set in conjunction with large coloured stones in rings. The table represented considerably greater labour. One corner of the regular octahedron was ground down until the artificial facet thus produced was half the width of the stone, while the opposite corner was slightly ground.
Still another century elapsed before the introduction of the rose pattern, which comprised twenty-four triangular facets and a flat base (Figs. 45–46), the stone being nearly hemispherical in shape. This style is said to have been the invention of Cardinal Mazarin, but probably he was the first to have diamonds of any considerable size cut in this form. At the present day only tiny stones are cut as roses.
