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Colored Stone Grading - Overall Quality Grade

Overall Quality Grade: In our appraisal and grading practice, we follow the general structure found in the Gem Guide wholesale gem pricing book published biannually by Richard Drucker, Gemworld International Inc. We find it to be the most reliable and consistent source available of market based price data for colored gemstones. Since price follows grade (or vice versa) our overall quality grades will reflect our opinion of the value of a gem within the market place.

On a scale of 1 to 10, we rate the combined effects of color, cut, and clarity, as well as rarity. Since color is the dominant feature for grading, we use the color grade as the initial grade and then apply adjustments for clarity and cut. So, a stone graded 9 for color could have clarity and cut grades of 6 and still be considered Extra Fine.

  • 8 - 10:  Extra Fine, the best of the best, rarely seen, and never cheap.  May have only minute defects in proportions or clarity or cut.  The top 5% almost never available set.
  • 6 - 8:  Fine. These are stones normally considered fine and sold as such in better to high-end jewelry stores.  Stones graded 8.5 and above fall into the top 10% of possible quality
  • 4 - 6:  Good. Quality grades, adequate in color and cut.  Seen in good to better jewelry stores.
  • 1 - 4:  Gemstones that fall into this category are what the trade calls "commercial".  Upper commercial, 3 – 4 can include clean stones with decent cut, but pale or less rare or desirable colors in material such as amethyst, aquamarine, garnets, peridot, blue topaz, and other more common gem material. Low commercial, 1 – 2 may be highly included, poorly cut, and/or deficient in color.

The integration of Color, Cut, and Clarity grades into the Overall Quality Grade is based on the following matrix, from Gem Guide Color price book, Fall/Winter 2008/2009, p. 10.

For a more complete explanation of colored stone grading, please review each of the additional documentations of the colored stone grading practices contained on this website under the following page titles:

Grading System for Colored Gems - Color

Grading System for Colored Gems - Cut

Grading System for Colored Gems - Clarity