AGA Round Brilliant Cut Grading Chart

LAST UPDATE ON: October 23rd, 2019

The tables below show the AGA Cut Grading system for round diamonds developed by D. S. Atlas and his laboratory Accredited Gem Appraisers. This system has been adopted by the National Association of Jewelry Appraisers (NAJA).

CUT CLASSES	Class1A	Class1B	Class 2A	Class 2B
	American Ideal Cut		International fine trade cut


Table %	53-58%	52-60%	51.5-63%	51-64%


Crown angleÂ°	34.0-34.7	33-35.1	32.1-35.8	31.6-36.4


Crown height %	14-16.3%	13.5-16.8%	11.6-17.9%	11.1-18.1%


Pavilion Depth %	42.8-43.2%	42.5-43.5%	42-44%	41.5-44.9%


Girdle Thickness: Word descriptions	Thin to Medium (1.0% to 3.0%) Medium to Slightly thick (1.7% to 4.5%)	Very thin to Slightly thick (0.4% to 4.5%) Thin to Slightly thick (1.0% to 4.5%)	Very thin to Slightly thick (0.4% to 4.5%)	Very thin to Thick (0.4% to 5.5%)


Total depth % Determined by factors already considered above	58-62.3%	58.3-62.99%	<58.3% >63%


Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Excellent –Very Good		Excellent toGood

CUT CLASSES	Class1A
	American Ideal Cut
Table %	53-58%
Crown angleÂ°	34.0-34.7
Crown height %	14-16.3%
Pavilion Depth %	42.8-43.2%
Girdle Thickness: Word descriptions	Thin to Medium (1.0% to 3.0%) Medium to Slightly thick (1.7% to 4.5%)
Total depth % Determined by factors already considered above	58-62.3%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Excellent -Very Good
CUT CLASSES	Class1B
	American Ideal Cut
Table %	52-60%
Crown angleÂ°	33-35.1
Crown height %	13.5-16.8%
Pavilion Depth %	42.5-43.5%
Girdle Thickness: Word descriptions	Very thin to Slightly thick (0.4% to 4.5%) Thin to Slightly thick (1.0% to 4.5%)
Total depth % Determined by factors already considered above	58.3-62.99%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Excellent -Very Good
CUT CLASSES	Class 2A
	International fine trade cut
Table %	51.5-63%
Crown angleÂ°	32.1-35.8
Crown height %	11.6-17.9%
Pavilion Depth %	42-44%
Girdle Thickness: Word descriptions	Very thin to Slightly thick (0.4% to 4.5%)
Total depth % Determined by factors already considered above	<58.3% >63%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Excellent toGood
CUT CLASSES	Class 2B
	International fine trade cut
Table %	51-64%
Crown angleÂ°	31.6-36.4
Crown height %	11.1-18.1%
Pavilion Depth %	41.5-44.9%
Girdle Thickness: Word descriptions	Very thin to Thick (0.4% to 5.5%)
Total depth % Determined by factors already considered above	<58.3% >63%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Excellent toGood

CUT CLASSES	Class 3A	Class 3B	Class 4A	Class 4B
	US domestic average cut		below average


Table %	50.5-67%	50-70%	49-72%	>72% <49%


Crown angleÂ°	30.1-37.9	29.6-39.4	29-40.5	<29 >40.5


Crown height %	9.6-19.3%	8.5-20.5%	7.8-21.8%	<7.8% >21.8%


Pavilion Depth %	41-45.5%	40.5-46%	38-48%	<38% >48%


Girdle Thickness: Word descriptions	Very thin to Very thick (0.4% to 7.0%)		Extremely thin to Extremely thick (0.0% to >7.0%)


Total depth %	<58.3% >63%


Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Good –Fair		Poor

CUT CLASSES	Class 3A
	US domestic average cut
Table %	50.5-67%
Crown angleÂ°	30.1-37.9
Crown height %	9.6-19.3%
Pavilion Depth %	41-45.5%
Girdle Thickness: Word descriptions	Very thin to Very thick (0.4% to 7.0%)
Total depth %	<58.3% >63%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Good -Fair
CUT CLASSES	Class 3B
	US domestic average cut
Table %	50-70%
Crown angleÂ°	29.6-39.4
Crown height %	8.5-20.5%
Pavilion Depth %	40.5-46%
Girdle Thickness: Word descriptions	Very thin to Very thick (0.4% to 7.0%)
Total depth %	<58.3% >63%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Good -Fair
CUT CLASSES	Class 4A
	below average
Table %	49-72%
Crown angleÂ°	29-40.5
Crown height %	7.8-21.8%
Pavilion Depth %	38-48%
Girdle Thickness: Word descriptions	Extremely thin to Extremely thick (0.0% to >7.0%)
Total depth %	<58.3% >63%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Poor
CUT CLASSES	Class 4B
	below average
Table %	>72% <49%
Crown angleÂ°	<29 >40.5
Crown height %	<7.8% >21.8%
Pavilion Depth %	<38% >48%
Girdle Thickness: Word descriptions	Extremely thin to Extremely thick (0.0% to >7.0%)
Total depth %	<58.3% >63%
Polish/Symmetry NOT A PRIMARY DETERMINING FACTOR	Poor

A diamond called a “Tolkowsky Cut” is only approximated by cut 1A. However, a “Tolkowsky Cut” is a very specifically calculated cut with the following parameters:

Table 53.0%, Crown Angle 34.6, Crown Height 16.2%,
Girdle Thickness app 1.7%, Pavilion Depth 43.1%. Many diamonds are improperly called “Tolkowsky Cut” when they are only approximating the parameters Tolkowsky formulated.

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