How Are Diamonds Evaluated?

Diamond evaluation uses a standardized system developed by the Gemological Institute of America (GIA) known as the 4Cs: Cut, Color, Clarity, and Carat weight.

Cut

Cut refers to how well the diamond's facets interact with light. A well-cut diamond reflects light beautifully, creating brilliance and fire. Cut grades range from Excellent to Poor. Cut is different from shape (round, oval, pear, etc.) — it refers to the quality of the cutting.

Color

Diamond color is graded on a scale from D (colorless) to Z (light yellow or brown). Colorless diamonds (D-F) are the most valuable. Near-colorless diamonds (G-J) also appear white to the naked eye. The difference between adjacent grades is often subtle and requires professional grading to identify.

Clarity

Clarity measures the presence of internal inclusions and surface blemishes. Grades range from Flawless (FL) to Included (I3). Most diamonds have some inclusions — the fewer and less visible, the more valuable. VS and SI clarity grades are common in jewelry.

Carat Weight

Carat weight measures the diamond's size. One carat equals 200 milligrams. Larger diamonds are rarer, so they command higher per-carat prices. Prices jump significantly at "magic sizes" — 1 carat, 2 carats, 3 carats.

Certification

A diamond grading certificate from a recognized laboratory (GIA, AGS) provides an independent assessment of the 4Cs. Having a certificate can increase confidence in the evaluation and sometimes the value.

Beyond the 4Cs

Other factors like fluorescence, polish, and symmetry can also affect value. Fancy colored diamonds (pink, blue, yellow) have their own grading system and can be extremely valuable.

Getting Your Diamond Evaluated

At NYC Jewelry Buyer, we evaluate diamonds using the 4Cs and professional tools. We explain our assessment clearly and make transparent offers. Call (646) 516-4623 for a free evaluation.