Diamonds can be cut in various shapes. The round brilliant is probably the best known shape. However, there are other shapes that can emphasize a diamond’s different features. The choice of a shape is best based on personal taste and the design of the jewelry.
The weight of a diamond is expressed in carats. One carat = 0.2 grams and one carat equals 100 points.
Practically all diamonds contain naturally occurring internal characteristics called inclusions. The size, nature, location and amount of inclusions determine a diamond’s clarity grade and affect its cost.
Diamonds come in a wide range of colors, with colorless diamonds traditionally being considered the most valuable. Most diamonds are graded on a scale using the letters of the alphabet, from D (colorless) through Z (a light yellow). It is difficult for the untrained eye to notice such variations in color unless stones are being compared side by side. The comparatively rare colored diamonds are known as fancy-colored and are also quite valuable. They range in hue from the more common yellow and brown to pink, blue, green, red, and black.
Most gemologists will agree that, of all the four C’s, cut is the most important. The cut of a diamond influences the way it reflects light, which in turn determines its brilliance. Even a diamond with perfect color and clarity may appear lifeless if it does not have a good cut. The cut grade is determined by the proportions and finish of a diamond. The proportions of various parts of the stone largely affect its fire, brilliance, and scintillation. Finish refers to a diamond’s polish and symmetry.
In a well cut diamond, most light enters through the table and travels to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to the observer's eye. If the stone is too deep, light is lost through the sides. If the stone is too shallow, the light that enters through the table reaches the facets and then 'leaks' out from the sides or bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means less brilliance.