April Birthstone: The Diamond
We don’t talk about birthstones every single month, but we love any opportunity to talk about our favorite gemstones. Diamonds are among our favorite gemstones. The diamond is the birthstone…
CUT CLASSES |
Class 1A |
Class 1B |
Class 2A |
Class 2B |
Class 3A |
Class 3B |
Class 4A |
Class 4B |
Ideal cut |
Premium cut |
International fine trade cut |
US domestic average cut |
below average |
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Table % |
55-60% |
53-61.5% |
52-62% |
51-64% |
51-67% |
49-70% |
48-72% |
>72% |
Crown Height % |
12-15% |
11.5-16% |
11-16.6% |
10.1-17.5% |
9-18% |
8.3-18.9% |
7.8-19.5% |
<7.8% |
Girdle thickness |
V. Thin to Sl. Thick |
V.Thin to Thick(0.4%-5.5%) |
Very Thin to Very Thick |
Extremely thin to |
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Total Depth % |
59.0-63.0% |
63.1-65.4% |
56-68.5% |
46-71% |
43-73% |
>73% |
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Length:Width Ratios |
Pear 1.50-1.75 |
1.26-1.99 |
|
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Polish/Symmetry |
Excellent to Good |
Good or Fair |
Poor to Fair |
CUT CLASSES |
Class 1A |
Ideal cut |
|
Table % |
55-60% |
Crown Height % |
12-15% |
Girdle thickness |
V. Thin to Sl. Thick |
Total Depth % |
59.0-63.0% |
Length:Width Ratios |
Pear 1.50-1.75 |
Polish/Symmetry |
Excellent to Good |
CUT CLASSES |
Class 1B |
Premium cut |
|
Table % |
53-61.5% |
Crown Height % |
11.5-16% |
Girdle thickness |
V. Thin to Sl. Thick |
Total Depth % |
59.0-63.0% |
Length:Width Ratios |
Pear 1.50-1.75 |
Polish/Symmetry |
Excellent to Good |
CUT CLASSES |
Class 2A |
International fine trade cut |
|
Table % |
52-62% |
Crown Height % |
11-16.6% |
Girdle thickness |
V. Thin to Sl. Thick |
Total Depth % |
59.0-63.0% |
Length:Width Ratios |
Pear 1.50-1.75 |
Polish/Symmetry |
Excellent to Good |
CUT CLASSES |
Class 2B |
International fine trade cut |
|
Table % |
51-64% |
Crown Height % |
10.1-17.5% |
Girdle thickness |
V.Thin to Thick(0.4%-5.5%) |
Total Depth % |
63.1-65.4% |
Length:Width Ratios |
Pear 1.50-1.75 |
Polish/Symmetry |
Excellent to Good |
CUT CLASSES |
Class 3A |
US domestic average cut |
|
Table % |
51-67% |
Crown Height % |
9-18% |
Girdle thickness |
Very Thin to Very Thick |
Total Depth % |
56-68.5% |
Length:Width Ratios |
1.26-1.99 |
Polish/Symmetry |
Good or Fair |
CUT CLASSES |
Class 3B |
US domestic average cut |
|
Table % |
49-70% |
Crown Height % |
8.3-18.9% |
Girdle thickness |
Very Thin to Very Thick |
Total Depth % |
46-71% |
Length:Width Ratios |
1.26-1.99 |
Polish/Symmetry |
Good or Fair |
CUT CLASSES |
Class 4A |
below average |
|
Table % |
48-72% |
Crown Height % |
7.8-19.5% |
Girdle thickness |
Extremely thin to |
Total Depth % |
43-73% |
Length:Width Ratios |
|
Polish/Symmetry |
Poor to Fair |
CUT CLASSES |
Class 4B |
below average |
|
Table % |
>72% |
Crown Height % |
<7.8% |
Girdle thickness |
Extremely thin to |
Total Depth % |
>73% |
Length:Width Ratios |
|
Polish/Symmetry |
Poor to Fair |
Courtesy of D.S. Atlas, Accredited Gem Appraisers, © AGA 1998-2004