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Grade 4 - Example 1 - RD19
Table: 62%
Crown >: 29°
Pav >: 39.6°
Stars: 50%
Lower gird: 75%
girdle: medium
culet: none
depth: 54.5%
polish: VG
symmetry: VG |
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| This diamond's grade is limited by its scintillation. The combination of a shallow crown angle and a somewhat shallow pavilion angle leads to a face-up appearance with a lack of contrast and general darkness. |
Click on the graphic to download the .gem file |
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Rhino's Review
An extreme shallow/shallow combo for angles. The 54.5% is the initial red flag here. Both MSU and HCA note the fish eye effect in this case (which is caused by a reflection of the girdle under the table) and the HCA is now accuratelygiving this diamond a hit in performance as well (despite a seemingly saturated IS image). MSU gives high marks for light return however the balance of lights/darks is really poor. Stones this shallow have a more obvious darkness to it than all previous examples and rightfully gets the Grade 4 classification. While your rarest diamonds will get the Grade 1 classification, as we head down the scale here stones getting this bad are sometimes equally as rare but in the bad sense. :-P
Grade 4 - Example 2 - RD33
Table: 56%
Crown >: 37°
Pav >: 44°
Stars: 55%
Lower girds: 70%
girdle: thin - med
culet: none
depth: 68%
polish: VG
symmetry: VG |
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| This diamond's grade is determined by its fire, scintillation and weight ratio. A slightly steep crown angle, combined with a steep paviloin angle and large total depth, cause this diamond to display a general darkness in the table area and very dark upper-girdle areas. |
Click on the graphic to download the .gem file |
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Rhino's Review
Really terrible combo of angles here. HCA fails to grade this due to the deep pavilion angles and rightfully so. The pavilion is really deep and evidence of a "nail head" is apparent by the darkness observed under the table. MSU also shows significantly lower scores for light return because of the steep/deep combo. The really short lower girdles (70%) coupled with these angles give the facets a really chunky look akin to many older cut diamonds on the market (ie. old european cuts & old mine cuts).
Grade 4 - Example 3 - RD37
Table: 70%
Crown >: 33.5°
Pav >: 40.2
Stars: 60%
Lower girds: 80%
girdle: sl.thick-thick
culet: none
depth: 56.9%
polish: G
symmetry: G |
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| This diamond's grade is limited by its brightness and scintillation. A large table and a somewhat shallow crown height, with this pavilion angle, causes a general darkness in this diamond along with a slight fisheye that becomes more evident when the diamond is tilted. |
Click on the graphic to download the .gem file |
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Rhino's Review
Oh yes... lack of brightness and scintillation is what characterizes these shallow combos. A total depth of 56.9% is the initial red flag. While the stone will have a considerably larger spread than normal, its coming at the expense of optics (as is the case with all shallow/shallows). *DEAD* would be one of the best ways to describe this one. You will be some decent fire in direct light conditions out of this one but why bother when you can get the best of all metrics with a Grade 1?
Final thoughts on Grade 4
More severe angles in way of steep/deeps & shallow/shallows. Visual performance proceeds to get worse and worse. It appears that GIA is right on track with their grading system. All three examples given in the Grade 4 designation have obvious red flags even if you were just looking at the most basic table/total depth info.
Example 1: 54.5% depth with 62% table.
Example 2: 68% depth with 56% table.
Example 3: 56.9% depth with a 70% table. Once again they gave us 2 shallow/shallows and 1 steep deep as examples. And just when you thought it couldn't get worse... |
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