- Joined
- Aug 15, 2000
- Messages
- 18,461
As some of you know most organizations and many learned and experianced appraisers believe that the Holloway Cut Adviser includes too many shallow proportioned diamonds. I have made a couple of adjustments and reduced that preference slightly over the past few years, but I am sticking to my guns.
I have had 2 basic arguements.
The first is intuitive - I have no science to back this one up. My idea is that dirt and oil gather mainly on the pavilion and so slightly deep diamonds suffer more from dirt induced leakage than should shallower stones.
The second idea came to me in a friendly discussion with Peter Yantzer, the Director of the AGS Lab. during a break at the First International Diamond Conference. Peter had just presented the idea of their Angular Spectrum Evaluation Tool (ASET), a Blue, Red and Green version of the Ideal-Scope, which will be one of the tools that the new grading systems will be based on. Where the ideal-scope has a black lens that minics 25 degrees of obstruction or obfscuration of lighting - the ASET Scope will replace the black with a blue source that blocks off 30 degrees of the available 180 degrees of potential lighting in an imaginary hemisphere.
They chose 30 degrees because that is the equivalent effect of viewing a diamond from a standard used by the US military - close to 10 inches for some sort of recorded typical sized head. I have always thought that 14 - 16 inches is a better standard based on 30 years of serving customers.
Anyway - many of you know that background. So during this discussion I suggested to Peter that the diamond ASET would reject because it had too much blue, and the Ideal-Scope still accepted - that the shallower Ideal-scope exception would make better earrings and pendant stones. peter laughed and conceeded my point.
So I decided to do a test. I replaced one of my wife Drena''s earring stones with a shallow stone. I do not have the exact numbers with me, but say both had the same pavilion angle of 40.8 degrees, then the standard stone has a crown of 35 degrees and the shallow stone is 32. Table sizes are very close.
Drena has been wearing these for about 3 months now, and there is no doubt that the shallow stone wins in all lighting environments. It was 2 weeks since they were cleaned - so tonight I wipped them out and took these 2 photo''s (not proffessionally - it is after 10pm here.)
So there is no doubt that people would avoid buying a diamond with the shallow stones ideal-scope image with all that blotchy darkness, yet this stone always outshines the "ideal cut" once they are dirty. When they are both clean - various peoples preferences are about 50:50 and when given the stones to hold and examine, young people with great eyesight and/ or people wearing dark clothes prefer the ''ideal-cut''. But because it is rude to examine someones earrings from 10 inches away, more people find the shallow stone to be brighter, and incidentally, more firey.
I have had 2 basic arguements.
The first is intuitive - I have no science to back this one up. My idea is that dirt and oil gather mainly on the pavilion and so slightly deep diamonds suffer more from dirt induced leakage than should shallower stones.
The second idea came to me in a friendly discussion with Peter Yantzer, the Director of the AGS Lab. during a break at the First International Diamond Conference. Peter had just presented the idea of their Angular Spectrum Evaluation Tool (ASET), a Blue, Red and Green version of the Ideal-Scope, which will be one of the tools that the new grading systems will be based on. Where the ideal-scope has a black lens that minics 25 degrees of obstruction or obfscuration of lighting - the ASET Scope will replace the black with a blue source that blocks off 30 degrees of the available 180 degrees of potential lighting in an imaginary hemisphere.
They chose 30 degrees because that is the equivalent effect of viewing a diamond from a standard used by the US military - close to 10 inches for some sort of recorded typical sized head. I have always thought that 14 - 16 inches is a better standard based on 30 years of serving customers.
Anyway - many of you know that background. So during this discussion I suggested to Peter that the diamond ASET would reject because it had too much blue, and the Ideal-Scope still accepted - that the shallower Ideal-scope exception would make better earrings and pendant stones. peter laughed and conceeded my point.
So I decided to do a test. I replaced one of my wife Drena''s earring stones with a shallow stone. I do not have the exact numbers with me, but say both had the same pavilion angle of 40.8 degrees, then the standard stone has a crown of 35 degrees and the shallow stone is 32. Table sizes are very close.
Drena has been wearing these for about 3 months now, and there is no doubt that the shallow stone wins in all lighting environments. It was 2 weeks since they were cleaned - so tonight I wipped them out and took these 2 photo''s (not proffessionally - it is after 10pm here.)
So there is no doubt that people would avoid buying a diamond with the shallow stones ideal-scope image with all that blotchy darkness, yet this stone always outshines the "ideal cut" once they are dirty. When they are both clean - various peoples preferences are about 50:50 and when given the stones to hold and examine, young people with great eyesight and/ or people wearing dark clothes prefer the ''ideal-cut''. But because it is rude to examine someones earrings from 10 inches away, more people find the shallow stone to be brighter, and incidentally, more firey.
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