…………………….AGA/NAJA Cut Class Grader………

 

AGA/NAJA CUT CLASS DIAMOND GRADING SCREENING TOOL


 

AGA Cut Class Rules For Determining “Overall” Cut Grade.

1A is the highest grade and 4B is the lowest grade

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1A grade: All characteristics are best when 1A, but may include a single 1B characteristic. You pay a premium for this cut and you should insist on getting exactly what you are paying for.

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1B grade: All characteristics need to be all 1B or 1A to 2B. Only a single class 2 characteristic is permitted. The class 2 characteristic should be within 2% or 2 degrees of the 1B characteristic.

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2A grade: All characteristics need to be 2A or 1A thru 2B. Only a single 2B parameter is permitted and it must be within 2% or 2 degrees of the 2A characteristic. (crown angle degree rounds only)

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2B grade: All characteristics need to be all 2B or 1A thru 3A. Only a single 3A characteristic is permitted and the 3A characteristic cannot be a very thick girdle or more than 1 degree too shallow a crown angle. The 3A characteristic must be within 2% or 1 degree of the 2B characteristic. (crown angle degree rounds only)

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3A grade: A stone may be all 3A or 1A thru 4A. Any characteristics of 4A must be within 2% or 1 degree the 3B characteristic. More than a single 4A characteristic and the stone cannot grade 3A. An overall class 4 girdle thickness cannot grade 3A overall. An overall girdle thickness is NOT determined by a single thin or thick area of a girdle. “Overall” has a meaning equivalent to “the major portion.” (crown angle degree rounds only)

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3B grade: As stone may be all 3B or 1A thru 4B. Any single characteristic of grade 4B must be within 2% or 1 degree of the 4A measurement. Only one class 4 characteristic permitted. Stones with class 4 extremely thick or extremely thin over all girdles may not be graded overall 3B. (crown angle degree rounds only)

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4A grade: A stone may be all 4A or 1A thru 4B. Only two 4B characteristics are permitted at most. (crown angle degree rounds only)

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4B grade: Is all 4B or may be any combination from 1A thru 4B. Stones with more than two 4B characteristics are automatically 4B.

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Specialty Cuts: This may include many forms of BRANDED DIAMONDS.

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There are diamonds that do not conform to the classic shape cut parameters and must be considered on an individual basis. ONE CANNOT GRADE UNUSUAL CUT DIAMONDS SOLELY ON ARBITRARY PARAMETERS.  EXPERIENCE IN EXAMINING DIAMONDS FOR EFFECTIVE AND PRECISE CUTTING IS REQUIRED FOR CUTS NOT COVERED IN THESE FOUR CHARTS OF TYPICAL STANDARD CUT DIAMONDS.

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Things to keep in mind for the finest fancy shapes:

Fancy Ideal Cuts:

All ideal cuts must look “beautiful”. Beauty is initially achieved through proper outline, careful facet arrangement, and facet matching. It is furthered by proper cut craftsmanship. The parameters of cut for relative show of size and for durability must be observed. Lastly, all ideal cuts exhibit relatively high, yet balanced amounts of brilliancy, scintillation and intensity. Fire may also be considered as an element of appearance in certain instances where it is featured.

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Needle-like shapes, high or dropped shoulders, bulging or flat sides, asymmetry, overly deep or too shallow all contribute to lack of beauty. Don’t blind your self to the obvious. Pear, marquise, oval and heart shaped diamonds have a range of best length to width ratio. Rectangular and square stones don’t have a length to width requirement; they do require 90 degree corners except in unusual circumstances or in special cuts.

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Personal preference for an odd shape, should have no effect on the grading for light performance or symmetry, but such a shape might fall out of the finest, commonly accepted, arrangement for beauty, or durability. This is a choice an informed consumer may choose to make, but it is not acceptable for a gemological lab or a dealer to provide incorrect data about an odd stone being “ideal” when it fails to truly fit a top quality category.

Special note about AGS OOO Princess cuts

Most AGS OOO Princess cuts tend to get a cut grade 2 using this tool and they are extremely beautiful stones. There are few standard cut princess cuts which would grade at a 1 grade, but those I have seen looked great to me when I examined them. However, the AGS0 is the special cut princess that has caught on with those who want a fine lab to grade a fine stone. So, don’t screen out AGS OOO stones based on not getting a 1 grade in this system. The AGS OOO princess is a special design which work very well with light, but tends to be a bit beyond the 1 range on the AGA/NAJA automated tool.

It is with absolute certainty that the vast majority of diamonds that have been sold to consumers in the past 80 years have been primarily in the 2B to 4A category of the AGA Cut Classes. Many, even most, of them look very nice or even excellent and most owners are very happy with these diamonds. Even today, with our much better knowledge of diamond cutting, most diamonds sold in the USA are 2B to 4A cut.  What does that say?  I think it says most people control their spending budget sufficiently that they will take a compromise on cut quality as well as compromising of color, clarity and weight.  Educating the consumer is still a work in progress.

If you have any problems with this application please contact Dave Atlas, datlas@datlas.com.   Please let us know what you entered.