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Grade 1 - Example 1 - RD01
Table: 54%
Crown >: 34°
Pav >: 40.8°
Stars: 50%
Lower girdle length: 75%
girdle: thin to medium
culet: none
depth: 61.2%
polish: VG
symmetry: VG |
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| This diamond scores in the top category for all grade setting determinants, and it has an even pattern of bright and dark areas. |
Click on the graphic to download the .gem file |
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Rhino's Review
Here is a diamond that is typical of what we purchase for inventory. I generally like my lower girdles a little longer but you'll find stones in our inventory that are comparable to these stats that are just downright beautiful. Amongst the H&A community this particular stone resembles a certain percentage of unbranded H&A's. There are many similarities to these particular sets of angles & %'s to that of an EightStar Diamond, yet not quite. An EightStar (or one cut similarly) will have closed off or eliminated all blatant whites (thus eliminating all leakage) and the little eight pointed star in the center will also come to 8 perfect points. The examples given for GIA's top grades reveal one important factor. They are not cherry picking to the level/degree of certain super ideal cut retailers or factories who feature such products (ie. like us!), at least with regards to optical symmetry (the H&A optical pattern/design). Another important fact to point out for those who have read and are fans of Fred Cuellars (questionable) book on how to buy a diamond ... Fred counsels his readers NOT to purchase diamonds with depths over 61%, yet here we have GIA's top grade class for cut and it's depth is 61.2%. Another pointof note is that GIA will not be making the separations it appeared they were going to regarding the lower girdles. In their report on DCLR (dispersed colored light return) they had concluded that the lengthening/shortening of the lower girdles dramaticallyaffected the diamonds appearance with DCLR increasing as lg length increased. Perhaps they will deem all lg lengths from 75% up to 85% in the same "Grade 1" category (or at least up to a certain percentage)?
Grade 1 - Example 2 - RD08
Table: 57%
Crown>:33.5°
Pavilion>:41.2°
Stars: 55%
lower gird: 85%
girdle: medium
culet: none
depth: 61.1%
polish: VG
symmetry: VG |
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| Although it's proportions are different from those for the first example, this diamond also scores in the top category for all grading setting determinants and has an even pattern of brightness and dark areas. |
Click on the graphic to download the .gem file |
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Rhino's Review
Drastically different minor facet combo here primarily due to the lower girdles which in this example are increased in length a full 10% (from 75% to 85%). There are paler reds under the table indicating light being returned at a weaker intensity in that location however more blacks are indicative of more light being returned at higher angles which compensate. As in the first example all facets are primarily functioning in the role of "mirror" (as opposed to windows) giving what GIA considers to be an excellent distribution of light. This diamond is also an excellent example of a "non-traditional" set of proportions that would have not received the "ideal" grade from the current AGS grading system. Crown angles of 33.5° would have caused it to receive a less than ideal grade. With this diamond GIA is demonstrating that you can get "ideal" brilliance from a set of proportions that are not traditionally considered to be "ideal" and they are to be applauded for this. MSU concur the results with excellent scores for brilliance/light return however the HCA rates the diamond with an undesirable score over 2.0 (2.5 in this case). In this circumstance I would take sides with GIA/MSU as the light being returned is sufficient to qualify for a Grade1 classification. If one were to compare these first two diamonds side by side there *can* be notable optical differences. The first diamond is generally described by observers as having fewer, yet broader/bolder flashes of light while this 2nd example having more tinier points/flashes of light in direct light conditions. The more areas within the diamond that are reflecting back light at high angles (75-90 degrees as indicated by the blacks) causes an increase in the amount of sparkle being returned to the eye while the former displays stronger and bolder flashes. The comparison is DEFINITELY not that of the pretty vs the ugly, but a comparison of 2 beautiful diamonds with different personalities. In suffuse light conditions the first diamond would have more prominent symmetry which would be observable to the eye while the 2nd (with skinnier arrows) would be less prominent, yet as GIA points out there is an even pattern of brightness and dark areas. This is an important thing to point out because this *contrast* that GIA is examining is NOT a contrast of light return vs. light leakage (MSU contrast) but is a contrast of facets reflecting back light vs. facets reflecting back shadows/colors of things obstructing light (i.e.. lights/darks). The Isee2 analysis is technology that digitally measures this feature of *brightness* and is a concept we first introduced in our tutorial on the subject which can be learned more about here. With regards to the 2 teachings on contrast I have always personally favored the "light/dark" contrast (Isee2) as opposed to the "light return/leakage" contrast (MSU/Holloway) as I don't feel a diamond should be rewarded for leaking more light. I am glad to see GIA concurs. One more point to note about this particular diamond is that GIA is notplacing any emphasis on the formation of a "Hearts" pattern (clefts, points or chevrons). They are focusing on the *face up* position which of course is the most important. Web sites that place too muchemphasis on the "hearts" (only observed face down) is losing site of what's really important to a diamonds "face up" appearance. And this is coming from a Hearts & Arrows nut here. :)
Grade 1 - Example 3 - RD20
Table: 61%
Crown>: 34.5°
Pav>: 40.8°
Stars: 55%
lower gird: 80%
girdle: medium
culet: none
depth: 59.6%
polish: VG
symmetry: VG
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| This diamond also scores in the top category for all grade setting determinants. |
Click on the graphic to download the .gem file |
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Rhino's Review
Another great example, specifically for those in the trade who favor the 60/60 combinations (although this diamond does not have *exactly* a 60% depth with a 60% table, it's darn close). Of course I'm going to point out that this diamond DOES not receive the top grade from GIA becauseof its table/depth combination but primarily because of the crown/pavilion angle relationship (34.5/40.8) which is the primary determining feature to determine whether facets will function as mirrors or windows. So 60/60 diamonds *can* indeed have ideal brilliance but not on that virtue alone. They must be cut to the proper angles in order to reflect back light properly. The primary feature to learn about this particular diamond is how little table size actually contributes to the (internal) reflective properties of the diamond. I have a particular fondness of this particular combination of major and minor facet proportions with the exception of the table size (I like em around the mid 50's) as this particular combination gives off a nice balance of brightness, fire and scintillation. Interestingly HCA results do not concur with this GIA grade as well receiving a mediocre score of over 2.0.
Final thoughts on Grade 1
There is general debate about which sets of proportions (primarily among the minor facets) produce the highest brilliance among those in the trade who feature such diamonds. The beautiful feature about GIA's system is that they allow many different combinations as tastes may differ from one person to the other. Some people prefer fewer broader chunkier flashes of light while others may prefer more smaller flashes. Grade 1 allows for *both* and all those that fall in between. What is consistent about the Grade 1 classification is that the greater majority of all facets must be functioning as mirrors (as opposed to windows) and that there is a balanced distribution of lights and darks within the diamond (contrast). Regarding current optical grading technologies introduced to our trade (BrillianceScope & Isee2), each of the 3 diamonds examined in this Grade 1 classification would receive no less than High White Light return, Very High Colored Light Return and High Scintillation as measured on the GemEx BrillianceScope (excellent results reflecting direct light appearance) and on the Isee2, high marks for brilliance and scintillation (excellent results reflecting suffuse light appearance). The Isee2 does not measure Fire (colored light return) but it does grade and measure optical symmetry which is the only category the example stones provided by GIA would most likely take a hit on as the Isee2 also grades the precision to which the diamonds optical symmetry has been cut (Arrows or face up precision of the pattern of lights/darks). As you'll see when we're exploring the other cut grade classifications, the MSU Jewelry Store lighting graphic (depicted in 2nd column) reflects the appearance GIA describes in their analysis which is why I have chosen to use these graphics in our tutorial. Another clear teaching from the Grade1 classification is that you do not have to have GIA Ex/Ex polish & symmetry to get the highest optics and apparently the Grade 1 classification. The dependence of excellent optics based on proper sets of proportions is something we have taught for years but now GIA confirms it is the proper sets of angles that will produce the highest brilliance. For those who feature precision cut Hearts & Arrows diamonds ... GIA has left you the opportunity to point out how your product even exceeds their grading standards as long as your Hearts & Arrows are cut to the proper proportions. So most technologies agree with GIA's assessment of Grade 1 classification with the exception of the HCA which gave 2 out of these 3 stones a score of over 2.0. |
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