Paul on AGS New Cut-Grading of Princesses

[moosewendy]

Date: 1/27/2005 2:54:59 PM
Author: oldminer
''The point is, it needs to be seen by someone who knows what to look for, not just measured by a machine. In my opinion, subjective human evaluation is too important a component in evaluating cut in a fancy to ever allow development of a meaningful machine generated cut grade''
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

reply:

I agree that today someone expert needs to be the one seeing the stone. A machine might be able to give measures which help someone know more than at present. We just don''t know how well this communication may develop. We are not near that stage yet....so for now, this is not what anything, including machines do for us. Even when machines measure ''beauty'' not every last one of us will agree that it works for them. There will be some vocal opponents and traditionalists. No one will be forced into agreement. If the work is done well, then there will be very few people who don''t get it.

Please don''t doubt the possibility of truly meaningful fancy cut diamond grading. Don''t commit yourself to a position that some of us know is incorrect. It isn''t wrong to be skeptical and questioning, but if you had more complete understanding of where the process is right now, you would have no doubt that meaningful fancy cut grade communication is almost a done deal. It isn''t so much what machines can''t do,, but the difficult human aspect of deciding upon standards that make sense. There are things happening in this arena.

Dave - I have, I believe, a pretty good understanding of where the process is now. Of course we can gather cut information about fancies. Interpreting the information in a meaningful way that the industry and the public will embrace is not just the end game - it''s the game itself. With many fancy shapes, no concensus exists as to what the ideal stone is supposed to look like. Whose standards are we going to use as the basis of our ideal model? If the GIA and the AGS and David Atlas all use different standards, who will be right? The answer is, you''ll have to look at the stone, just like you do now. With round stones, the process was easier because everyone used tolkowsky as an accepted starting point. Square princesses are relatively easy, because the shape is consistent and symmetrical. Other fancies present much more difficult problems. How much bow-tie is acceptable in a marquis or pear shape? Is a smaller looking stone with almost no bowtie inherently better or worse than a bigger looking stone with a small bowtie? A machine will never answer thses questions, and I''m not sure the quest to do so is even a worthwhile venture.

 

[oldminer]

Your points are good ones to make and I understand. What excites me has been the opportunity to work with people who have great expectations of doing what you may consider an impossible task. It has not been easy, but I have made the time committment to go much further down this pathway along with them. I believe many varieties of advice and research will be tossed out into the arena for criticism and suggestions. This is the way change comes. It would be a great thing for me to be part of a team that made the seemingly impossible an everyday reality. This is what many different labs and researchers are attempting to do.

I see it as a complex process, but possible. Progress along these lines is one of the lifeboats of the industry. We want to keep the business a viable one and do an honest job.

 

[Garry H (Cut Nut)]

Moosewendy the main variant in the size of a bow tie is not inherent in the diamond - it is inherent in the observers eye sight / viewing distance and head type / hair size and color etc.

So in to some extent there can be no universal cut grade system.

 

[moosewendy]

Garry - While bowties can be more or less obvious in diffferent lighting conditions, they exist because of how the diamond is cut, so they are definitely a cut characteristic (though an extremely complicated one). But, I agree with you, sensitivity to them is a matter of taste. So is preference for the different kinds of life characterized by slightly different pavilion angles. That''s precisely why I believe the creation of a universal cut grade for fancies other than square princesses is a task best left undone. I do think that a univeral standard could be applied to square princesses, because, unlike other fancies, the shape is consistent and symmetrical, making the stones both easier to cut and to evaluate.

 

[Rank Amateur]

Has Leonid''s questions about "where" and "when" the cut details will be available been answered? Maybe I missed it.

 

[Garry H (Cut Nut)]

Date: 1/28/2005 12

7

5 PM
Author: moosewendy
Garry - While bowties can be more or less obvious in diffferent lighting conditions, they exist because of how the diamond is cut, so they are definitely a cut characteristic (though an extremely complicated one

Please do this experiment Moosewendy.
Peep thru a small hole in a sheet of white paper at a diamond with a bow tie and tell us what you see?

 

[moosewendy]

Garry- what''s your point. Are you saying that because bowties are not equally visible under all lighting and viewing conditions they don''t really exist? Don''t all cut characteristics vary in appearance based on factors like lighting, viewing distance, obscuration, etc? Why, under identical lighting conditions when viewed by the same person, with the same hair at the same angle, at the same time, will one diamond show a severe bowtie and another none at all? Why can I recut a stone with a strong bowtie and substantially reduce it? Personally, I doubt that people who dislike fancies with bowties will take great comfort in knowing that the bowtie will disappear if their diamond is viewed through a small hole in a white piece of paper.

In my opinion, bowties are a huge problem in standardizing cut grades for fancies, both because they are hard to impirically quantify, and because sensitivity to them is subjective. Do you disagree that a meaningful cut grade standard would have to take into account the existence and extent of a bowtie?

 

[Garry H (Cut Nut)]

Any meaningful cut grade takes into account poorly dispersed darkness in a diaond at some predetermined amount of obsuration of light sources from imaginary head / body.

I prefer 25degrees or 6 inch head at 14 inches viewing distance.
Others like AGS and FS use 30 degrees and GIA has even played with 40 or more degrees.

 

[moosewendy]

Garry - Does this mean that cut grades are meaningful only to the extent that the diamond is viewed in a manner consistent with the set of assumptions used by the particular cut grade scheme? If the viewing distance is changed by 12 inches, do the results change materially? Why do you prefer a different set of assumptions than the AGS? If these choices are subjective, then aren''t the results subjective as well?

 

[Garry H (Cut Nut)]

These topics have been well discussed on 2 or 3 ''aGS new cut grade'' topics.

Yes - cut grade systems like the AGS and GIA need 1 or more standardised lighting environments etc.

AGS think 10 inches is the standard viewing distance which knocks out shallower stones and makes almost all well cut marquise have a bad bow tie

 

[moosewendy]

Garry-just one last question, and then let''s move on with our lives. Do you think the same set of assumptions are necessarily appropriate for rounds and fancies? It seems to me that a set of assumptions which grades marquises with severe bowties better than those without should probably be rethought.