Why are the 4 Cs of cut, clarity, color, and carat weight so important? The 4 Cs are used throughout the world to classify the rarity of diamonds. Diamonds with the combination of the highest 4 C ratings are more rare.
CUT determines the scintillation and sparkle of a diamond. In order to achieve maximum brilliance, each of the stone's facets and angles must be placed in exact geometric relation to one another. Diamonds are cut into a number of shapes, the most popular are round, marquise, oval, pear, heart and emerald; and the choice is largely a matter of personal preference.
CLARITY refers to the quantity, size, position, nature, color and relief of inclusion in a diamond. Inclusions refer to minute crystals, feathers and clouds that can be found in most diamonds. Truly flawless diamonds are extremely rare.
COLOR quality is important since usually the more colorless the diamond, the greater its rarity and value. The majority contain very slight traces of yellow, brown or gray. A single increase in color grade can dramatically change a diamond's value. Diamonds occur by rare incidences of nature in shades and intensities of yellow, pink, blue, green and red.
CARAT is a term for the diamond's weight and not for its size. It is important to stress that size alone is almost meaningless unless you consider cut, clarity and color. A large stone has little value without brilliance, purity and high-grade color. One carat is divided into 100 "points", so that a diamond of 75 points weighs .75 carat. Carat weight is the easiest of the 4 Cs to determine.
4 Cs of Diamonds | Colored Gemstones