What Do the Letters in Grading a Diamond Mean?

Diamonds are graded on four different aspects.

Diamonds are graded on four different scales, known as the "Four C's" and represented by letters, words and numbers. A combination of the diamond's carat weight, color, clarity and cut will determine its overall quality.

History

To help standardize the methods used to describe the quality of diamonds, the Gemological Institute of America developed a standardized system in the 1940s and 1950s. These quality indicators are called the GIA International Diamond Grading System.

Clarity

A diamond's clarity refers to the absence of exterior and interior blemishes, called inclusions. The best diamonds are graded FL for Flawless, followed by IF (Internally Flawless), VVS1 and VVS2 (Very, Very Slightly Included), VS1 and VS2 (Very Slightly Included), SI1 and SI2 (Slightly Included), plus I1, I2, and I3 (Included).

Color

The color of a diamond is graded on a scale of letters from D to Z, with D indicating the most colorless diamonds and Z indicating very yellow diamonds. Colorless diamonds are generally the most valuable, although there is also a specialty market for vividly colored diamonds.

Carat

Diamonds are weighed in carats, with one carat equal to 0.2g. One point equals 100 carats, so a .75-carat diamond weighs 0.15g and can be referred to as a 75-point diamond.

Cut

The last of the 4Cs is cut, which is ranked on a scale of Excellent, Very Good, Good, Fair and Poor. Its placement on the scale is determined by three factors: brilliance, fire and scintillation.

References

• Gemological Institute of America: About the Four C's