Thank you Wink - The article has been quite some time in the making, as we wanted to be certain we were representing the interests of the major labs correctly. To the end, we had great cooperation and input from both AGSL and GIA Laboratories. I know Brian would like to thank Garry Holloway, Sergey Sivovolenko and Marty Haske for peer review & input as well.
Brian is out of the country right now so I will field the Qs and he can blame me if I misspeak.
We have only a small slice of the world of diamonds, so we'll not make a blanket statement, but for our purposes - and congruent with this study - we saw influence at 6-7 degrees depending on the specific diamond. Other configs may show influence with less. Still others might have room for more. We did not have such a candidate but others may. We have ACP 3.0 - 4.0 in abundance but not so many to select from beyond that. The 6.8 was a diamond we saved specifically for this study and in that case we agree with the reduction from both labs.
Brian could comment better than I can about that. I haven't compared photorealistic sims to the diamonds so much. I use DC as strictly technical and am working my way backwards from the advanced edits, ASET/IS sims etc... I think I entered through the kitchen on that count. I'll meet the rest of you fellows in the dining room for drinks as soon as I can.
The effects are noted on page 2. The observations were kept neutral, which is something our peers encouraged. Instead of saying "Bright colored flashes are present at ACD 0 but become muted and eventually invisible from ACD 3-5," we noted "Reduction in performance begins with ACD >= 3°. Girdle facets fall off in performance especially fast (severe greens)."
Since we know you''re one of the few & the proud who will actually read the whole thing (and call us out if we mislabeled something!) we thank you kindly, Miss Belle.
Thank you Garry. Brian is the chef. I just garnish the salads and drizzle chocolate over the desserts around here. We both appreciate your input.Date: 9/13/2006 10:06:34 PM
Author: Garry H (Cut Nut)
John can you check the top contrast score on the normal stone in page 8 please?
(for all your work. Now I would like to see this done in steps of 0.2 degrees for pavilion and 0.5 degrees for crown angles on table sizes 50% to 63% please John. Then we can have some idea of the effects of painting and digging on diamond appearance. can you do that before lunch tomorrow?)
Really though John, you are to be congratulated.
...
Brian and John, this article is filled with an extraordinary amount of info. Thank you so much for putting it together. I think I get the gist (hopefully) and reading between the lines, most of the ACAs and ES stones that are painted are painted from .5 to ACP 3-6 at the most for the new line with the classics falling between the range of .5 to 2.5 and most new lines falling from 3.5-6 at the outside for ACP; is that accurate? I''m making these assumptions based on the Idealscope images which are very recognizable. Please feel free to correct me if I misspeak.
Personally, I think that the whole painting thing is funny. When we''re talking ACA new line crown only painting, I''ve seen it next to a stone that has negligible if any painting (both superideal). Sealing the edges of the stone (how I think of painting) (no leakage) really makes them pop in low light as well as great broadfire flash for huge sparks of color. I love the affect and will not ever own a different kind of stone. People literally take note from across the room. It''s fun to watch their mouths drop open. Kudos to you and Brian for this article.
shay
It may be helpful to know that, due to cutting equipment, concentrations are found near 0, 3.75 and 7.50 degrees. With regard to our specific brand: ACA Classic can be slightly over 0 degrees ACP, but not enough to greatly influence the IS image. ACA New Line have ACP <> 3.75 degrees (one physical click). Some of the diamonds we used in the study ranged outside ACA criteria to determine lab thresholds. The 6.8 degree candidate was cut some time ago and we agree with the reduction from both labs. Our interaction with AGS/GIA was motivated by a desire for enlightenment. It served to reinforce Brian's paradigms.
We hear this from people, but not always so well-described. Thank you for the observations Shay. It’s always a pleasure to hear from you.
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