Home » categories » rare book library » Williams: Diamond Mines South Africa II

Ch. 18: Cutting and Polishing

Ch. 18: Cutting and Polishing Page of 396 Ch. 18: Cutting and Polishing Text size:minus plus Restore normal size   Mail page  Print this page
CUTTING AND POLISHING
177
represents the part beneath the girdle, which being twice as thick as the upper section is cut with six steps instead of three. In closely studying this step cut and the table cut it was discovered that the diamond crystallized in thin laminae or plates, and that it might be split into very thin sections resembling plates of mica. By taking advantage of these " lines of cleavage," as they are called, many large diamonds were split into thin leaves and used as faces of small pictures enclosed in lockets. At Queen Victoria's coronation this thin sheet diamond was so common that many distinguished guests were favored with a gift of their own likenesses encased in golden frames and covered with a diamond instead of a glass face.
In the plates below, Fig. 15 and Fig. 16, facets of the "rose cut" pattern are represented. It will be seen that the bottom
design, which is called the " Hol­land," groups twenty-four facets, but a simpler style known as the "Antwerp rose" shows facets
ranging from six to sixteen. This rose cut is a very convenient style to adopt for fragments which have been cleft from large stones, or for diamonds which are imperfect in their crystal­lization on one side. If well proportioned, the depth of the rose must be one-half its breadth at the base.
In the rose cut diamond every facet is a triangle and all meet at the central apex, forming a cupola. When the facets on large stones number thirty-two, the dealers call it " flam minghi " or " half brilliant." A common practice of the trade is to obtain a second " flam minghi " of the same size, but cut in quartz crystal or even in glass, and glue their bases together with gum mastic, thus forming the " briolet" or " brilliolet," which is palmed off for a pure diamond. Briolets are pear-shaped or oval stones, having neither table, culet, nor edge, but covered with triangular-shaped facets, sometimes pierced at their points of greatest diameter, to be suspended on an axis.
Ch. 18: Cutting and Polishing Page of 396 Ch. 18: Cutting and Polishing
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page