The 4 C's are the common language every jeweler uses to describe a diamond: cut, color, clarity and carat weight. Two stones of the same size can look and cost very differently, and the 4 C's explain why.

Cut

Cut is how well the facets are shaped and arranged to return light. It is the C that most affects sparkle, so it is the last one worth compromising on. Cut is graded from Excellent down to Poor on round stones.

Color

Color measures how colorless a diamond is, on a scale from D (colorless) to Z (light yellow or brown). Most of the difference between neighboring grades is invisible once the stone is set, especially in yellow or rose gold.

Clarity

Clarity describes tiny natural marks called inclusions and blemishes. The scale runs from Flawless to Included. A stone graded VS2 or SI1 is often clean to the eye and costs much less than a Flawless one.

Carat

Carat is weight, not size. One carat equals 0.2 grams. Shape changes how big a stone looks, so an oval or elongated cushion can look larger than a round of the same weight.

How to balance them

• Choose an Excellent cut first.
• Pick a color and clarity grade that look clean to the eye, not the highest on paper.
• Spend what is left on carat weight.