There is a difference in a gemstone’s value as a gemstone and its value as a component of jewelry. First, when a loose stone with an ideal tone is set in jewelry, its tone will appear darker and its beauty may be hidden. One should keep this in mind when going to the source to buy loose gemstones for jewelry. Second, as long as it is beautiful, a thinner stone is better. Calculating from the refractive index, the ideal total depth for colored stone is from 60 to 70 percent. If it is attractive, however, a stone with a total depth of 50 to 60 percent allows a wider range of construction options when used in jewelry, and makes it easier to create something with a pleasing style. Large sizes of fancy-shaped diamonds are often seen with total depths of 50 to 60 percent, and some of these have a very beautiful appearance.

The sapphires on the right are arranged with a thin stone on top, a medium depth in the center, and a thick stone on the bottom. If the face-up beauty of these were the same, the one on top would be best as a component in jewelry. Because of its lower carat weight, the per-carat price is likely to be higher. However, becoming preoccupied with the notion of “thinner is better” may cause one to forget beauty, or give rise to other problems, such as the girdle in an overly thin stone becoming a sharp angle and more susceptible to chipping.

As for thick stones, one of the main problems is bulge, which leaves excess weight in the pavilion and also detracts from the stone’s face-up beauty. However, the color from the rough may be concentrated near the surface in that area, making it necessary to leave the bulge there. Gemstones are made by nature, and there is no way to avoid their imperfections. Understanding this and making an overall decision that will allow the creation of comfortable jewelry is the role of the true professional jeweler.