The standard use of measurement for diamond weight is the carat. A carat equals 1/5 of a gram (or 1/142 of an ounce). Each carat is further divided into points, each point representing 1/100th of a carat. Sometimes diamonds will be referred to in "points" Such as fifty points which means 0.50carat or 1/2 carat. Think of it as pennies to the dollar. 100 points is 1carat.
Clarity is the evaluation of a diamond's internal and external characteristics. Inclusions are internal, that is, inside the diamond. Think of them as birthmarks within the stone, each is unique. Blemishes are usually very small and are only on the surface of diamonds such as scratches, nicks or pits. Diamonds are graded with 10 power magnification then by evaluating the size, location, nature, number, and color of all the inclusions and blemishes, a clarity grade is assigned. The fewer the inclusions or blemishes, the more desirable and rare the diamond!
A diamond's color is graded on an alphabetical scale from D-Z, with D being colorless and Z being light yellow. Beyond Z, a diamond is considered to be "Fancy" color. A truly colorless diamond is extremely rare. Most diamonds possess varying degrees of yellow, gray or brown and small, subtle differences in color can make a substantial difference in value. Diamonds are color graded by gemologists facedown next to "master" diamonds of known color.
Of all the 4 Cs, cut has the greatest effect on a diamond's beauty. The cut of diamond is the key that unlocks the hidden beauty within a piece of rough.
Diamonds have a unique ability to manipulate light efficiently that is what creates the beautiful brilliance, sparkle and scintillation... the rainbows of color!
Cut can also refer to a stone shape or outline. Such as Round cut, Emerald cut or Oval cut.