Colored Gemstone Grading

Value Factors

Color • Cut • Clarity • Carat Weight

Grading Scale

Even though colored gemstones have their 4 C's, they are evaluated somewhat differently than in diamond grading.

COLOR:

Considered the most important. Each gemstone has its own specific colors, and each has its most desired color which will vary from one geographic area to another. Generally the richer (darker, but not too dark) and brighter the color and the more even color distribution, the prettier and more expensive the gemstone will be. The duller, more zoned and lighter colored gemstone will usually be more reasonable. Color grade can be 70% of the total value of the gemstone.

Hue: The essential impression of color that we notice immediately (Red, Blue, Greenish Yellow, etc)
Tone: The color's lightness or darkness.      (Light,     Medium,      Dark)
Saturation: Purity of the color. The more grayish or brownish, the lower the saturation and the duller the color. Gemstones that have real dark tone, or real light one (washed out) never reach a high saturation. The desired appearance is appealing and bright and could be called "Vivid".

6 Vivid-Bright • 5 •  4-3 Medium • 2 • 1 Dull Brown-Gray

CUT:

Quality/Polish/Finish 

Excellent 10 - 8  •  Very Good 7 - 6  •   Good 5 - 4  •   Fair 3 - 1

CLARITY:

The degree of freedom from visible characteristics put there by Mother Nature during the stone's growth. Clarity grades for colored gemstones are categorized into three areas: Type I that are generally very clean and are penalized more than Type II for having any inclusions and Type III, where inclusions are expected and not penalized as heavily as Types I & II.

Type I

Aquamarine, Chrysoberyl, Citrine, Topaz, Smoky Quartz, Green Tourmaline, Tanzanite and Blue Zircon.

Type II

Alexandrite, Amethyst, Garnets, Peridot, Iolite, Ruby, Sapphire, Spinel, all Tourmaline except red and green.

Type III

Emeralds, Red & Pink Tourmalines.

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COLOR & CLARITY GRADING