The 4 C's

Diamonds are graded by four criteria called “The Four Cs”: carat (how heavy it is), clarity (how clear the diamond is of internal flaws), color (how close to colorless it is), and cut (how the diamond is shaped). Each is important, and the best diamonds have high ratings in all four criteria.

Carat

Most people think that a carat refers to the size of a diamond, but it actually is a measure of weight. A diamond grading report or certificate will specify a diamond’s weight in “carats”. The word carat refers to the weight of a diamond. One carat is 0.2 grams, or 200 milligrams.

Clarity

Clarity measures the internal defects (called inclusions) in a diamond. The inclusions can come from imperfections such as tiny cracks, from foreign matter trapped in the diamond structure, or from other causes. Almost all diamonds have some inclusions, but the better diamonds have inclusions that can’t be seen by the naked eye. Diamonds are graded by the number, size, color, location, orientation and visibility of these inclusions.

Color

A perfect diamond is completely transparent and has no color at all. However, the perfect diamond is extremely rare. Instead, most diamonds have some chemical impurity in them that causes some coloring of the diamond. The amount of color is judged on a scale of letters from D (near perfect) to K (noticeably tinted).

Cut

The cut of the diamond affects how it reflects light and hence how brilliant it looks. There are mathematical formulas for determining the best angles and lengths to cut each facet to reflect the most light. The diamond is judged by these formulas when the cutting is completed.