The Four Cs of Diamonds
The “Four Cs of diamonds” refer to the stone’s cut, color, clarity, and carat (weight or size). The four Cs are the primary criteria the American Gem Society and others use to grade gems and determine their value and price.
A diamond’s cut is arguably the most important of the 4 Cs because it has the biggest impact on the stone’s brilliance. The diamond’s cut affects how light is reflected through the gem and, as a result, how beautiful and fiery it appears to the human eye.
Most people think of diamonds as white or clear, but in reality they come in a wide range of colors, from transparent or “colorless” to yellow or brown. In general, diamonds that are graded colorless are the most valuable while diamonds with a faint yellow or brown hue are less valuable. Diamond color is graded on a letter scale, with D, E, and F being the highest “colorless” grades. Some other colored diamonds (blue for example) are unique and therefore may be extremely valuable, although these are typically excluded from this grading system.
Diamonds are a natural substance and, as a result, most of them are not perfect. They come out of the ground with imperfections. In the gem world these are called inclusions. Diamond graders use magnifiers to spot these inclusions and determine how they impact the gem’s appearance. This grade is called diamond clarity. Diamonds without an inclusions are rarer and more valuable. Many inclusions, however, are not visible to the naked eye.
Diamond carat is an expression of the gem’s size. A carat is a metric unit of weight equal to one fifth of a gram.