. Precious stones, a popular account of their characters, occurrence and applications, with an introduction to their determination, for mineralogists, lapidaries, jewellers, etc. With an appendix on pearls and coral. Precious stones; Pearls; Corals. FORMS OF CUTTING 77 or shortened (Fig. 7 a, b, c). The outline of the girdle may approach that of a square, as in the figure, or it may be oblong. This form of cutting is peculiarly adapted to stones of an elongated shape, and it brings out their lustre to a marked degree; the elongated brilliant facets seem to compensate for any lack of depth in t
. Precious stones, a popular account of their characters, occurrence and applications, with an introduction to their determination, for mineralogists, lapidaries, jewellers, etc. With an appendix on pearls and coral. Precious stones; Pearls; Corals. FORMS OF CUTTING 77 or shortened (Fig. 7 a, b, c). The outline of the girdle may approach that of a square, as in the figure, or it may be oblong. This form of cutting is peculiarly adapted to stones of an elongated shape, and it brings out their lustre to a marked degree; the elongated brilliant facets seem to compensate for any lack of depth in the lower portion of the stone. Another similar form is that known as the Maltese cross (Fig. 8 a, b, c), so called from the ci-uciform arrangement of its facets. Other similar forms exist, differing but slightly from those already described ; a detailed account of these is therefore unnecessary. .'5. Table-cut.—This term includes a number of forms, all of which are more or less related to, and may be derived from, a four-sided double pyramid or regular octahedron. This octahedral form is the natural crystalline form of many diamonds, and it may sometimes be seen in the stones of jewellery which dates back to the time when no cutting of the rough stones was attempted, but the preparation of the stones for ornamental purposes was confined to the polishing of the natural faces of the crystals. Such stones date back to very ancient times, and are known as point-stones. The table-cut, and other forms related to it, are derived from the octahedron by the greater or less truncation of two opposite corners (Plate IV., Figs 11 to 16); a few additional facets may be given to the upper portion of the stone (Figs. 11, 13, 14, 16). The typical table-stone is derived from an octahedron by cutting two opposite corners to an equal amount. The upper and lower portions of the stone are then exact replicas the one of the other, and the table is of the same size and shape as the culet, the outli
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