The thickness of the crown should be one-third of the total thickness of the stone, and the table should be about four-ninths of the breadth of the stone. These proportions are based on the optical properties of the diamond, and it will be seen that a considerable amount of care and patience will be required to cut a given stone, which is generally quite small, to these specifications.
With other transparent stones, the facets are somewhat modified if cut in this form, and their number and inclination to each other will depend upon the individual optical properties of the specimen. Such stones as white zircon, white topaz, and white sapphire usually have fewer facets than the diamond. Sapphire and ruby are often brilliant cut, but usually without the full number of facets also. Emerald is seldom seen in brilliant form, since its color dispersion is low, and the trap cut brings out its color to better advantage.
We will now recapitulate the various facets of the brilliant form of cutting in the order of manufacture. First, a facet is cut which slopes from the table to the girdle. This is the bezel facet. Opposite this, another is cut, and a further two similar facets makes the table square in shape. Four more bezel facets follow, which makes the table octagonal.