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Strategy for Comparing Color

Confused on Color

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In regards to this specific loose stone I am considering, if the jeweler claims it's an "I", then it sounds reasonable that I compare it to a GIA graded "H" and a GIA graded "J". Thus, if the loose stone appears to be between the two, then it's likely the jeweler's color grade is accurate. Is this a good strategy?


Confused on Color

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This is basically correct but there are several pitfalls that you should watch out for. GIA has different grading standards for master stones than for stones submitted to the lab. The primary difference is a minimum clarity, some cut limitations and a standard for fluorescence but the acceptable ranges of color are also quite a bit tighter. Be sure you are using a stone that was graded by GIA as a master stone and not simply one that was graded for the market by their lab. Variations in the lighting can also make a difference. It’s important to do the color grading in a standardized environment because changes in lighting and environment can lead to distinctly different conclusions. Lastly, it’s very important that both the subject stone and the masters be carefully cleaned. Minor amounts of contaminants on any of the stones can make for important differences.


Neil Beaty


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