The Brilliant Cut

The styles of cut may be grouped as follows: 1, those bounded by plane surfaces only; 2, those bounded by curved surfaces only; 3, those bounded by both curved and plane surfaces. The styles of the first group are best applicable to transparent stones, as the diamond, emerald, and ruby; they are brilliant cut, double brilliant or Lisbon cut, half brilliant or single cut, trap or split brilliant cut, Portuguese cut, star cut, rose cut, or briolette, step brilliant or mixed cut, table cut, and the twentieth-century cut; this is a combination of facets that was experimented with but not very successfully about the year 1903. Styles of the second and third groups are best adapted to translucent and opaque stones, such as the opal, turquoise, moonstone, and cat's-eye. Both the first and second styles are applied to garnets, which are cut either with facets or convex (or en cabochon), and when thus cut they are termed carbuncles. The styles of the second group are bounded by curved surfaces; they are the single cabochon cut, double cabochon cut, hollow cabochon cut, and tallow top cabochon cut. The third division of styles are those bounded by curved and plane surfaces, represented by the mixed cabochon cut.

The brilliant cut could be represented by two truncated pyramids, placed base to base; the upper pyramid, the crown, is truncated in a manner to give a large plane surface; the lower one, the pavilion, ends almost in a point. The line of junction of the bases of the two pyramids is called the girdle. While there are many modifications of this style, as to the size, mutual proportions, and number of facets, the facets in the perfect brilliant number fifty-eight. The top facet is called the table, and is formed by removing one third of the thickness of the fundamental octahedron; the bottom facet is called the culet, or collet, and is formed by removing one eighteenth part of the stone's thickness. The triangular facets touching the table or summit of the crown are called star facets; those touching the girdle are divided into two groups, skill facets and skew facets. The corner facets touching the table and the girdle, when on the crown, and the culet and girdle, when on the pavilion, are called, respectively, bezel or bizel facets, and pavilion facets. A summary of the number of facets and their distribution is as follows: 1 table, 16 skill facets, 16 skew facets, 8 star facets, 8 quoins, 4 bezel facets, 4 pavilion facets, and one culet. Sometimes the cut is modified by adding extra facets around the culet, making sixty-six in all.

The brilliant cut is especially applicable to the diamond; when perfect it should be proportioned as follows: From the table to the girdle, one third, and from the girdle to the culet two thirds of the total. The diameter of the table should be four ninths of the breadth of the stone. These proportions when applied to other stones than the diamond are modified to suit the individual optical constants of the gem.

The double brilliant, or Lisbon cut, is a form with two rows of lozenge-shaped facets, and three rows of triangular-shaped facets, seventy-four in all.

The half brilliant, single, or old English cut is the simplest form of the brilliant and is now generally employed for small stones; when the top is cut so as to form an eight-pointed star it is called the English single cut.