A diamond's cut grade is a abjective measure of a diamond's light performance, or , what we generally think of as sparkle. When a diamond is cut with the proper proportions, light is returned out of the top of the diamond (which gemologist refer to as the table). If it is cut to shallow, light leaks out of the bottom; too deep and it escapes out of the side.
Color manifests itself in a diamond as a pale yellow. THis is why a diamond's color grade is based on its lack of color. Because color differences are detectable by placing diamonds next to each other, it is important to keep the color of diamonds in the same piece with in one grade of each other.
Clarity refers to the tiny, natural imperfections that are present in all but the rarest diamonds. The less inclusions, the better the clarity. Gemoligist refer to these imperfections by a variety of technical names, including blemishes and inclusions. Because these imperfetions tend to be microscopic, they do not generally affect a diamond beauty in any discernible way.
Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. The Carat is the standard unit of weight for diamonds and other gemstones, takes its name from the carob seed. Because these small seeds had a fairly uniform weight, early gem traders used them as counterweights in their balance scales. The modern metric carat, equal to 0.2 grams, was adopted by the United States in 1913 and other countries soon after. Today, a carat weighs exactly the same in every corner of the world.