Even if you have never been shopping for diamond jewelry, you have probably heard about the four Cs used to classify diamonds-clarity, cut, carat and color. These collective metrics are used throughout the world to determine the value of individual diamonds, with diamonds exhibiting the most desirable combinations of clarity, cut, carat weight and color rising to the top as the most universally unique and highest valued gems.

Clarity refers to the extent of inclusions, or natural features such as fractures present in the diamond that originated from its formation deep within the earth. A diamond's cut describes the design and proportions of the diamond after it is crafted by a diamond cutter, an art form that manifests itself in the diamond's outward appearance and brilliance. Carat is a concrete description of a diamond's weight, with one carat representing a weight of 200 milligrams. Color is a diamond quality that generally refers to the extent to which a diamond is colorless. The Gemological Institute of America (GIA) has established a widely accepted color scale to rate diamonds falling in the normal color spectrum, which ranges from colorless to yellow. Diamonds which fall closer to the colorless end of the color spectrum are generally considered more valuable than yellow or brown tinted diamonds of equivalent clarity, cut and carat weight. Intensely colored diamonds are the exception, their rarity and beauty making them extremely valuable and exotic despite being far from colorless.

Although many people perceive all diamonds to be colorless, true colorless diamonds are extremely rare, and thus the most valuable on the GIA color scale. A majority of diamonds commonly used in jewelry such as engagement rings and have a tint of yellow or brown, placing them in the normal color range. Though slight variations in the color of diamonds are to be expected, the difference among various shades is usually indistinguishable to the untrained eye.

While diamonds in the normal color range are the most common, diamonds form within the earth in an array of colorful hues. Diamonds in vibrant colors such as pink, yellow, green and blue, called fancy colored diamonds, are highly sought after by diamond connoisseurs and jewelry consumers alike. The rarity and splendor of such exotic diamonds contributes to their high value, and is the reason that colored diamonds are often attractions at museums and exhibits. The famous and fabled 45.52 carat Hope Diamond on display at the Smithsonian Institution since 1958 is a prime example, requiring dedicated security measures and personnel of its own.

Like white diamonds, the value of a fancy colored diamond is determined in part by the collective value of its four Cs. However, the color attribute becomes a more significant dynamic in the valuation of a colored diamond. Rather than being evaluated on its lack of color, a colored diamond is valued based on the quality of its hue, intensity and consistency.