Rose, Step, and Cabochon

The trap brilliant, or split brilliant, differs from the brilliant in having the foundation squares divided horizontally into two triangular facets, forty-two in all.

The Portuguese cut has two rows of rhomboidal and three rows of triangular facets above and below the girdle.

In the star cut the table is hexagonal in shape, and is one fourth of the diameter of the stone; from the table spring six equilateral triangles, whose apexes touch the girdle, and these triangles, by the prolongation of their points, form a star.

The crown of the rose cut consists of triangular or star facets, whose apexes meet at the point or crown of the rose. The base lines of these star facets form the base lines for a row of skill facets whose apexes touch the girdle, leaving spaces which are cut into two facets. The base may be either flat or the bottom may be cut like the crown, making a double rose or briolette cut. The shape of a rose-cut stone may be circular, oval, or, indeed, any other to which the rough stone may be adapted.

In the trap or step cut, the facets extend longitudinally around the stone from the table to the girdle, and from the girdle to the culet. There are usually but two or three tiers of step facets from the table to the girdle, while the number of steps from the girdle to the culet depends upon the thickness and colour of the stone. This style of cut is best adapted to coloured stones.

The form of the step brilliant, or mixed cut, from culet to girdle is the same as that of the trap cut, while from the girdle to the table the stone is brilliant cut, or the opposite.

The table cut consists of a greatly developed table and culet meeting the girdle with bevelled edges. Occasionally the eight-edge facets are replaced by a border of sixteen or more facets.

The twentieth-century cut contains more facets than the brilliant and is differently shaped and arranged. Originally this style was designed with eighty-eight facets and proportions similar to the American brilliant, but with a greater height from the girdle to the centre of the table, caused by the facets replacing the table being carried to a low pyramidal point in the centre. Subsequently the style was modified, the stone being cut thinner and with but eighty facets, the central top facets being almost flat. This cut is helpful in some cases, especially to shallow stones, but it probably exceeds the limit of efficiency in the effort to increase the surface reflection and dispersion of light rays, and experience has not demonstrated its success.

The cabochon cuts represent different degrees of convexity above the girdle, and beneath a concave, plane, or slightly convex surface. The double cabochon is customarily cut with a smaller curvature on the base than on the crown. The single cabochon is a characteristic cut for the turquoise. The hollow cabochon is best for deep-coloured transparent stones. The mixed cabochon has either the edge or side, or both, faceted. The degree of convexity in the various cabochon cuts is made to depend upon the nature of the stone to which the cut is to be applied. The cabochon cuts are specifically within the province of the lapidary.