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What does GIA mean?

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Hi. GIA stands for Gemological Institute of America, which is a highly respected institute for gemological research and education in the United States. GIA operates the Gem Trade Laboratory, which is GIA's sole diamond-grading authority. When a diamond is "GIA certified," it means it has been graded for the "4 Cs" by GIA gemologists, and a grading report from the Gem Trade Laboratory (GIA Diamond Grading Report or GIA Diamond Dossier) should accompany any GIA-certified diamond.


I'm planning to make a diamond purchase soon, so I've done lots and lots of research on the subject, and the general consensus seems to be that GIA certificates are the most prestigious because GIA grading is consistent and conservative. The only exception seems to be that AGS (American Gem Society) certificates are preferable if the primary concern is for diamond cut -- AGS is the only reputable lab that offers a cut grade at this time, though I hear GIA is currently working on standards for its own cut grade. In any case, GIA reports include measurements, depth and table percentages, and symmetry and polish grades, all of which provide a lot of good information about cut. I hope this helps.

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When a diamond is "GIA certified," it means it has been graded for the "4 Cs" by GIA gemologists


Actually for the record, the GIA-GTL (Gemological Institute of America Gem Trade Laboratory) does not provide a grade for the 4C's they really only publish grades for the 3C's at this point in time: Carat weight, Color and Clarity... The 4th C - Cut is not touched by the GIA which only provides the total depth and table diameter measurements on their lab reports along with a girdle measurement... In order to determine the Cut Grade of a diamond the GIA would need to publish the Crown Angle and Pavilion Angle measurements on their lab report... They don't do this now, but they're talking about doing so in the future. In the mean time, be sure to obtain the Crown & Pavilion Angle measurements for any diamond you are considering by obtaining a Sarin or OGI computerized proportions analysis.


Robin & Todd Gray

Focus on Ideal and Super Ideal Cut Diamonds

Email: diamonds[at]

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