Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a polished diamond. Of the 4 “C”s it is the cut that has the most influence on the diamond’s brilliance and beauty. A finished diamond’s proportions affect its light performance, which in turn affects it beauty and overall appeal. If light enters through the crown of a poorly proportioned diamond, it might exit through the pavilion, making the diamond look dark and unattractive. Diamonds with good proportions, symmetry, and polish make better use of light, and will be bright, fiery, and sparkling.
The elements of diamond proportions are
The diamond industry has long known that some proportion combinations make light perform better than others. In recent years, however, scientists in the GIA Research department and the GIA Gem Trade Laboratory have shown that there are many possible variations and combinations of proportions that will maximize brilliance and fire in round diamonds. In addition, GIA researchers have found that facet size and placement might also play a role in how much fire a diamond displays. Even so, researchers are quick to point out that their research in not yet complete. Round brilliants characteristically have balanced proportions, and they usually deliver excellent brilliance, fire and scintillation. A round brilliant’s face-up shape (its girdle outline) usually won’t affect its appearance unless the outline is really irregular. With fancy shapes (all shapes other than round) not all stones of a given shape are equally attractive. Table size, crown angle, and pavilion depth have something to do with this, of course, but it also depends on how pleasing the shape’s girdle outline is. An evaluation of girdle outline also involves other, more practical considerations. For example, shape itself can make a difference: A bench jeweler might have a difficult time setting a stone with an unusual shape. Visual appeal and practical considerations often work together to result in a diamond that is both beautiful and durable. Rectangular cuts, for example, have beveled corners for a variety of reasons. First, beveled corners add visual appeal: They give a dynamic quality to what would otherwise be a plain rectangle. They are also practical: They provide a secure setting area for prongs and make the stone less vulnerable to chipping. The size of the beveled corners matters, too. If they are too narrow, they give the stone an odd look and make it difficult to set. Shoulders are located near both ends of oval shapes and near the rounded end of pear shapes. They should be gently and evenly rounded. Squaring the shoulders makes the diamond weigh more, but it makes pears look triangular and ovals look chunky. In the same way, a distorted curve on the lobes of a heart can make it look squashed or flat. On marquises, pears, and hearts, the sides near the points are called wings. They should form attractive arches. If they are too flat, they make the stone look too narrow. If they are too rounded, they make it look short and stubby. |
