AGS's Color Grading Questions

[Luna]

Hi. I received a diamond with AGS DQD yesterday and I went to see a graduate gemologist for verification of the diamond. Everything was fine except the color. He used the very sophisticated machine to test it and the result was F instead of E which was on the AGS DQD. He tested it again but the result was again F. Now, I really do not know what to do. I has never happened to me before. Is AGS's color grading more lenient than GIA's? Should I ask the second opinion ? Should I return the diamod? Please help me. Thank you very much.

 

[Garry H (Cut Nut)]

I have been asked to be Australian agent for the leading colorimeter, and my evidence all suggests these instruments are far from fool proof, so i have made a bad economic decision and refused to sell them.
The AGS has a very slightly better reputation than GIA for consistancy of grading, but both are considered the very best.

 

[oldminer]

A colorimeter is NOT as accurate as grading with the eyes along with properly graded master stones in the correct lighting.Reliance on a colorimeter is NOT the accepted or most accurate way to do diamond color grading. I have owned three modern colorimeters and know from first hand expeience that they work, but not as well as a skilled gemologist with the proper master stones, good vision, and correct lighting.The best thing one can say about a colorimeter is that one cannot argue with a machine. Right or wrong, the machine has no ears and no emotion. I'd say that if the device reads F that the E grade is very possibly the correct one. I'd be far more concerned if the colorimeter read H or some other lower color..You can bet that AGS color grading is super accurate. I believe the AGS lab cares a great deal about building a reputation for accuracy and reliability...I'd bank on the E grade if it was my stone.
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David Atlas
Accredited Gem Appraisers