The 4 C’s of diamonds—Cut, Color, Clarity, and Carat weight—are the universal standard established by the GIA to evaluate a diamond's quality, rarity, and value. Cut determines brilliance, color measures lack of color, clarity assesses internal/external flaws, and carat measures weight. Cut is generally considered the most important factor for sparkle.
- Cut (Sparkle): Evaluates how a diamond's facets interact with light. It is ranked from Excellent to Poor. A well-cut stone (like "Excellent" or "Ideal") will appear more brilliant, while a poor cut can make a diamond look dull regardless of its other qualities.
- Color (Colorless to Yellow): Measures the absence of color in white diamonds, graded on a D-to-Z scale. D is colorless (most rare/expensive), while Z has a light yellow or brown tint.
- Clarity (Purity): Measures the internal inclusions and surface blemishes. Ratings range from Flawless (FL) to Included (I1-I3). VS2 or SI1 grades often offer the best value as they are typically "eye-clean".
- Carat Weight (Size): Measures the diamond's weight (1 carat = 200 milligrams). As carat weight increases, price increases exponentially due to rarity, though a slightly lower carat weight (e.g., 0.95 vs. 1.0) can offer better value.