How does diamond grading work? Diamond grading is based on the international “4C” system (Carat, Color, Clarity, Cut), defined primarily by the Gemological Institute of America (GIA) to determine a diamond’s quality and value. The factors include weight (Carat), absence of color (D–Z), clarity (from FL/IF to I3), color (from D to Z), and cut quality.
Carat – Size
The weight of a diamond is measured in carats. One carat equals 100 points, or 0.2 grams.
Clarity – Purity
The clarity scale is based on the number, size, location, and visibility of impurities and imperfections present in the diamond. These imperfections affect the diamond’s brilliance and the reflections it emits.
Color
The most valuable diamond is completely colorless. Diamonds are graded on a scale ranging from D (colorless) to Z (yellow tint).
Cut
Diamonds can be cut into various shapes. Some of the most popular are: brilliant, oval, marquise, pear, heart, emerald, princess, and radiant.
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