How the number of chevron facets change the character of a princess-cut

[Rhino]

Good mornin Dave,

Date: 11/7/2006 1:11:49 PM
Author: oldminer
Paul, I was not trying to take you off topic. Sorry if you felt it was headed somewhere you didn''t want it to go.

The number of facets certainly changes the looks and performance levels of diamonds even when they grade AGS 0 or have generally similar Sarin readings. I only wondered if you felt that grading the quality of craftsmanship would be a good thing to separate from the grading of light performance?

I''d think people would care less about the number of Chevron facets, but would buy a diamond that looked great to their own eyes and judgment. Symmetry and craftsmanship are necessary to success of getting a beautiful stone, but the ultimate test is how a person feels a stone looks.

Diamond cutters might get ''accidental'' light performance, but I doubt they would try to have any accidents due to the risk and cost. Of course, one sees low light performance with excellent craftsmanship quite frequently. It seems you feel there ought to be a separation of light grading and craftsmanship grading. This was my own thought and I believed it went well with the thread''s premise of a craftsman''s choice in cutting along with getting a beautiful result.

I agree with your comments regarding grading the craftsmanship seperately from light performance/visual appearance/optics.

In essence GIA/AGS does it but only includes traditional polish/symmetry grading. Ie. in each of their systems a diamond can have Id/Ex polish/symmetry yet not get Id/Ex grade for the overall cut grade if light performance doesn''t meet the criteria established within the parameters they''ve laid out.

IMO the element of optical symmetry should be taken into account as well since aligning the facets on an optical basis requires a certain level of precision that you don''t necessarily need to have to get Id/Ex polish/symmetry. Factories that take these extra steps to ensure precise optical symmetry, IMO should be rewarded for their efforts. I wouldn''t necessarily limit the best optical symmetry grade for H&A types alone either. There are stones that don''t have traditional H&A patterning which are cut just as precise and have perfectly symmetrical patterns coupled with superior light performance. We''ve began to do this with each of the rounds in our inventory already.

Are you thinking along the lines of optical symmetry grading to be included in "craftsmanship" and do you also desire to apply this to squares like Princess Cuts? Curious to hear your thoughts. Perhaps some of us can get our heads together on the subject and develope a set of standards by which to grade optical symmetry in squares.

Peace,

 

[Paul-Antwerp]

Date: 11/10/2006 7:35:29 AM
Author: oldminer

Cut Craftsmanship is partly symmetry and polish, but I include good design of the facets just like one would look at the appearance of a building to judge the quality of its architecture and not judge it by how well only the stucco was applied. There are many features of craftsmanship in diamonds that go beyond polish and symmetry. Since diamonds are costly, I really think part of craftsmanship is the creation of something beautiful, too. It is not a simple measure to grade craftsmanship, but craftsmanship alone, does not make a the entire image of a diamond.

As the decision of 2, 3, 4 or more lines of chevrons is not a decision of good or bad, and it is only a matter of taste and not performance, I see no way in which this can be graded. It can only be described.

Live long,

 

[Regular Guy]

Date: 11/10/2006 7:35:29 AM
Author: oldminer
Light Behavior folks, like myself, are definitely on the side of the consumer having factual data with which to help them find the ''flavor'' of what they most prefer. I imagine few will opt for the very highest measured perfomance as their tastes or budget may well dictate otherwise. Who is to say that the highest graded light performance will look prettiest? It certainly is not anyone I know. I hope this clears that matter up. In my mind there is no ''pinnacle'' of desired performance. It remains a matter of taste. We do have ''engineer types'' who demand maximum performance measures. Measuring light performance satisfies their specific goals, but it is a pursuit of those who place numbers above visual evidence. I cooperate with them, but please don''t think we are in that camp in our personal opinions.

After reading this Dave, I later realized this long time view you''ve shared above may be effectively seen with a different paradigm.

When I wrote recently about the idea that maybe AGS was, while "better," not different as they claim. You responded in here. The idea seems to be that the question...

If a tree falls in the forest, and no one is there to hear it, does it make a sound...

...should be asked, before you start to measure sound, and report its measurements. That is, again, to say...I think you''ve misapplied what an engineer would be interested in, really. Maximum performance would not, I don''t think, be of interest, to anyone as a theoretical principle, outside of how preferred looks are understood. Measurements should (and can!) be reconciled back to preferences, to provide...if necessary to say it this way (since it is really only documenting here a middle step) a new hierarchy, that would be consistent with predicted preferences. That would please both your engineers, and most anybody, since their preferences should not vary for either group considerably.

In a previous post, I also wrote of a worry that you might be creating dissonance for yourself. Maybe taking this approach can represent the seed of an idea to reduce that considerably, since where you say above: "...please don''t think we are in that camp in our personal opinions..." I would really like to see you excited about the work you are doing for your customers, because you DO believe in it, yourself!

Warm regards,

 

[Rhino]

Date: 11/7/2006 10:38:41 AM
Author: Cehrabehra

Date: 11/7/2006 9:29:12 AM
Author: oldminer
Paul , do you feel it would be best to grade the quality of craftmanship separately from quality or amount of light performance? Or, would you prefer the two ''grades'' to be combined?

I''m not paul, but *I* think they should be separate. ALSO I think the different numbers of chevrons should be labeled the same way I wish they''d manage cushions a bit better instead of having an endless array of cuts under one heading.

I hear ya Cehra. It''d make life a little simpler eh? Not sure if this was answered already but at least with AGS graded princess cuts the consumer can determine the number of chevrons by looking at the face-up/down graph on the AGS Reports. The face down view will show the number of chevrons. I cropped these from the AGS Reports of the 2 stones in that vid.

All the best,

 

[He Scores]

Interesting thread you started Paul.

I personally have a vested interest in seeing craftsmanship judged in ADDITION to performance. The main reason is that workmanship is only one of six factors affecting performance.

In Rhino''s video as an example, there could be many other factors that make a difference in the fire other than the sole difference being the number of chevrons.

I viewed before and after data on some improved princess cuts at a lab and the performance was greatly enhanced by the corner mains on bottom being placed close to the 40.75 degree mark.

As Paul pointed out, top cut rounds will generally be cut to those angles closely associated with the Tolkowsky theoretical. Why is this? Primarily because it is this critical angle that separates light into the spectral colors. Brilliandeering facets disperse it into larger or smaller patterns like Rhino pointed out.


Bill Bray
Diamond Cutter

 

[Paul-Antwerp]

You are right, Rhino, I forgot about that drawing.

It is a pity, though, that AGS in their drawing is using the same size for all chevrons. It would look much better if the drawing of the 2-chevron-stone would show the true size of the facets, which is about double that of the drawing.

Live long,

 

[Rhino]

Date: 11/7/2006 9:01:23 PM
Author: Cehrabehra

Date: 11/7/2006 1:11:49 PM
Author: oldminer
Paul, I was not trying to take you off topic. Sorry if you felt it was headed somewhere you didn''t want it to go.

The number of facets certainly changes the looks and performance levels of diamonds even when they grade AGS 0 or have generally similar Sarin readings. I only wondered if you felt that grading the quality of craftsmanship would be a good thing to separate from the grading of light performance?

I''d think people would care less about the number of Chevron facets, but would buy a diamond that looked great to their own eyes and judgment. Symmetry and craftsmanship are necessary to success of getting a beautiful stone, but the ultimate test is how a person feels a stone looks.

Diamond cutters might get ''accidental'' light performance, but I doubt they would try to have any accidents due to the risk and cost. Of course, one sees low light performance with excellent craftsmanship quite frequently. It seems you feel there ought to be a separation of light grading and craftsmanship grading. This was my own thought and I believed it went well with the thread''s premise of a craftsman''s choice in cutting along with getting a beautiful result.

I partially agree with this david - but if I already knew which pattern I preferred I''d likely request those same parameters. Like with a round - I know I''d want very short LGF unless the stone was like 4 carats. If I''d never seen any stone before, then no, the number would mean nothing to me. Once you have the info though, you can narrow the search down - I still think it''s important to list the number of chevrons, just like I think it''s important to list the LGF (and probably crown facet info - though I haven''t studied that *yet* hehe)

I agree Cehra. The thing is I don''t think most folks care about the number of chevrons perse as most princess cuts on the market (including AGS Ideals) primarily consist of 3-4 chevron pavilions. The more folks get educated on the subject however and view them, only then will demand increase for one style over another. The folks we''ve showed this comparison to have been a pretty even split that I can recall. Perhaps I should hold a survey (once Tim gets back from vacation) and tally up to see where most consumer preference lies with this?

Peace,

 

[Rhino]

Date: 11/9/2006 11:57:31 AM
Author: Paul-Antwerp

Date: 11/9/2006 11:38:08 AM
Author: Cehrabehra
I don''t think we need to disagree because I don''t think there''s a difference (necessarily) in light performance between 2 and say 6 chevrons other than maybe a more consistent white with less obvious scint... I''m talking about the ''flavor'' also - and think it''s good to know this info so that someone who walks into a store and sees a pattern they like can say ''yeah, I like 4 chevrons, can we go bigger/whiter/clearer?'' I overlooked that last paragraph of David''s.. I agree that light performance should be apart from ''craftmanship'' though I hadn''t thought of it as craftmanship before. Coming into diamonds and quickly finding a love/hate relationship with cushions, I developed a love for facet placement and find GIA certs woefully inadequate in that department - particularly when you have helium and other instruments out there that could bind those facts right in at certificate level. My gripe with light performance issues in general is that everything seems to be pointing toward some single pinacle ideal that ignores other flavors... I think Garry with the BIC and FIC (should he fine tune this more) is on the right track to developing these flavors. I think that Princess cuts have the same opportunity in terms of fire and brightness AND in pattern flavor.

I do think that LGF plays an equally significant roll if you look at extremes. A 2 chevron princess vs an 8 chevron princess.... LGF of 90 vs LGF of 40 (OEC like). These are facet pattern issues that play with the light already determined in ''light performance''. So on the one hand you ask yourself, ''how much light return am I getting?'' and on the other you ask yourself, ''what are these facets DOING with this light?''

If I were sitting at the round table with those that count in all of this, I would want, on every certificate, info on light performance (and when fire can be accurately measured and not just anticipated based on numbers) further broken down into white light/fire, info on facet cut (angles, true shapes, facets) to determine flavors, clarity including inclusion plots, finishing info (polish/sym) which to me is craftsmanship where facet cut is design... that''s all I can think of... and until I actually think someone cares what I think I''m not going to worry too much if I''ve forgotten something haha

I do not think that we disagree on the light performance-part. I think that I disagreed with a small remark of Dave on this. And you are giving a nice synonym, by using ''flavor'' for what I called ''look'' or ''character''.

If we compare the impact of LGF on rounds with the number of chevron-lines, I would say that the difference in ''flavor'' between 2 and 3 lines of chevrons in princess-cuts can be compared to the difference between 40 and 90 LGF-length. A difference between 2 and 4 lines is even more.

So, we definitely agree on more than on what we disagree. (Weird sentence, I wonder if it is grammatically correct)

Live long,

LOL... my thoughts exactly Paul after reading this exchange.

 

[Paul-Antwerp]

Date: 11/10/2006 9:54:48 AM
Author: He Scores

I viewed before and after data on some improved princess cuts at a lab and the performance was greatly enhanced by the corner mains on bottom being placed close to the 40.75 degree mark.

Bill Bray
Diamond Cutter

Hey Bill, how are you doing?

I fully agree with your remark on the angle of the corner mains. It has repercussions though, which many dinosaurs continue to interpret as negative.

The corner mains define the pavilion depth, and an angle around 40.75 creates a pavilion depth of around 62%. Add to this a minimum girdle of 2% and a decent crown height of 11%, and we are already at a total depth of 75%. I have written a number of articles on how depth in a princess-cut is traditionally misunderstood, and how incorrect the old-time-standards and ideas are.

Still, too many people, professionals as well as consumers do not understand this, and I still see it reflected in the design-decisions of competing AGS-0''s.

Live long,

 

[Rhino]

Date: 11/10/2006 6:04:56 AM
Author: Paul-Antwerp
Hey Rhino, nice video.

What was weird, when watching it this morning at home, the stone seemed very rectangular on the screen. Now, I watched it again, at ease, at the office, and the stones look very square.

Anyway, it is a very nice illustration of a big difference. And here you were comparing 2 with 3 chevron-lines, where I guess that a huge number of princess-cuts will have 4 chevron-lines.

Live long,

Thanks Paul. Having made this type of comparison yourself I know you are familiar with the visual differences which is why I was interested in your input. I think the video communicates it as effectively as possible short of seeing them live of course.

I photographed the 2 stones in the same lighting as the vid but IMO the photography just didn''t do justice to the comparison.

I agree with your comment too about most stones being of the 3-4 chevron flavor. Personally I LOVE the different appearance of the 2 chevron but then I like having/seeing variety.

Your vid probs may have been due to the browser you were viewing them in. I''m still experimenting with different vid formats (Quicktime, Windows Media, Flash, Real etc.) but Windows media was just there when I was making the file and renders a little faster. Once again, thanks for your input.

Peace,

 

[Rhino]

Date: 11/10/2006 9:41:17 AM
Author: Paul-Antwerp

Date: 11/10/2006 7:35:29 AM
Author: oldminer

Cut Craftsmanship is partly symmetry and polish, but I include good design of the facets just like one would look at the appearance of a building to judge the quality of its architecture and not judge it by how well only the stucco was applied. There are many features of craftsmanship in diamonds that go beyond polish and symmetry. Since diamonds are costly, I really think part of craftsmanship is the creation of something beautiful, too. It is not a simple measure to grade craftsmanship, but craftsmanship alone, does not make a the entire image of a diamond.

As the decision of 2, 3, 4 or more lines of chevrons is not a decision of good or bad, and it is only a matter of taste and not performance, I see no way in which this can be graded. It can only be described.

Live long,

While I agree with what you''re saying here Paul, what I believe Dave is trying to communicate is that while the number of chevrons should be noted in helping a consumer determine which flavor they like most ... the optical arrangement of those facets should be graded and taken into account.

For example there are many manufacturers of 3-4 chevron princess cuts but not all of them are cut to the same level of precision (craftsmanship) which is identifiable through scopes like the ASET and various red reflectors. This is what I believe Dave is trying to convey. Correct me if I''m wrong Dave.

Peace,

 

[Rhino]

Date: 11/10/2006 9:54:48 AM
Author: He Scores

Interesting thread you started Paul.

I personally have a vested interest in seeing craftsmanship judged in ADDITION to performance. The main reason is that workmanship is only one of six factors affecting performance.

In Rhino''s video as an example, there could be many other factors that make a difference in the fire other than the sole difference being the number of chevrons.

I viewed before and after data on some improved princess cuts at a lab and the performance was greatly enhanced by the corner mains on bottom being placed close to the 40.75 degree mark.

As Paul pointed out, top cut rounds will generally be cut to those angles closely associated with the Tolkowsky theoretical. Why is this? Primarily because it is this critical angle that separates light into the spectral colors. Brilliandeering facets disperse it into larger or smaller patterns like Rhino pointed out.


Bill Bray
Diamond Cutter

Goor morning there Mr. Bray!

I couldn''t agree with this statement more and thank you for pointing it out. Before even considering the number of chevrons, the foundation of proper angle combinations must be laid if superior light refraction/reflection will occur in the diamond be it 2 chevron, 3 or 4. How are things up around your parts? Yesterday it was actually warm here in NY and today is off to a good start too.

Peace,

 

[He Scores]

Good morning to you Rhino...

64° and sunny today.

The other thing that I noticed about chevrons is that the larger the stone, the more likely hood of more chevrons. I am currently fixing several in the 1.5ct. range and they have four chevrons where small stones will have the two or three. From a cutting standpoint, it''s harder to put 4 on a small stone.

Bill

 

[Rhino]

Date: 11/10/2006 9:54:53 AM
Author: Paul-Antwerp
You are right, Rhino, I forgot about that drawing.

It is a pity, though, that AGS in their drawing is using the same size for all chevrons. It would look much better if the drawing of the 2-chevron-stone would show the true size of the facets, which is about double that of the drawing.

Live long,

I agree. Here''s the comparison of the AGS graphic as compared to an actual scan of the stone. What you say above is right on, about double the size.

 

[Rhino]

Date: 11/10/2006 10:39:03 AM
Author: He Scores

Good morning to you Rhino...

64° and sunny today.

The other thing that I noticed about chevrons is that the larger the stone, the more likely hood of more chevrons. I am currently fixing several in the 1.5ct. range and they have four chevrons where small stones will have the two or three. From a cutting standpoint, it''s harder to put 4 on a small stone.

Bill

Understood. Also ... would it be more difficult to get Ideal/Ex polish/symmetry witih more chevrons since there are more facets to concern yourself with?

 

[He Scores]

Re: chevron depiction.

Actually a two chevron stone could look both ways depending on how much they are "dug". The narrower chevrons will also make the large girdle break larger, while larger chevrons will reduce the size of them.

How high the chevrons are will also make a difference in appearance of the stone by reducing the area of the main corners.

All of these things are "elements" of facet making that my scoring system takes into account. When people ask me if i score fancies and I say "not yet", you can readily see the complications that may exist. It can be done though, since the elements of making a facet are all the same, except different priorities.

Bill

 

[He Scores]

Date: 11/10/2006 10:45:26 AM
Author: Rhino

Date: 11/10/2006 10:39:03 AM
Author: He Scores

Good morning to you Rhino...

64° and sunny today.

The other thing that I noticed about chevrons is that the larger the stone, the more likely hood of more chevrons. I am currently fixing several in the 1.5ct. range and they have four chevrons where small stones will have the two or three. From a cutting standpoint, it''s harder to put 4 on a small stone.

Bill

Understood. Also ... would it be more difficult to get Ideal/Ex polish/symmetry witih more chevrons since there are more facets to concern yourself with?

It''s like typing a letter. The more pages you have to type, the more likelyhood of making errors. So yes, Rhino, you hit the nail on the head.

Bill

 

[Cehrabehra]

Date: 11/10/2006 7:35:29 AM
Author: oldminer
Light Behavior folks, like myself, are definitely on the side of the consumer having factual data with which to help them find the ''flavor'' of what they most prefer. I imagine few will opt for the very highest measured perfomance as their tastes or budget may well dictate otherwise. Who is to say that the highest graded light performance will look prettiest? It certainly is not anyone I know. I hope this clears that matter up. In my mind there is no ''pinnacle'' of desired performance. It remains a matter of taste. We do have ''engineer types'' who demand maximum performance measures. Measuring light performance satisfies their specific goals, but it is a pursuit of those who place numbers above visual evidence. I cooperate with them, but please don''t think we are in that camp in our personal opinions.

Cut Craftsmanship is partly symmetry and polish, but I include good design of the facets just like one would look at the appearance of a building to judge the quality of its architecture and not judge it by how well only the stucco was applied. There are many features of craftsmanship in diamonds that go beyond polish and symmetry. Since diamonds are costly, I really think part of craftsmanship is the creation of something beautiful, too. It is not a simple measure to grade craftsmanship, but craftsmanship alone, does not make a the entire image of a diamond.

I totally disagree with you that design is part of craftmanship. I mean sure, a good cutter will pick the correct design for a particular stone, but other than that design aspects are vastly different than craftmanship aspects. Just now in a cushion thread someone was asking about 3 stones and one could have an OMC cut, one can have a 4 pav main cut, and one can have a crushed ice 24 cut - talk about different flavors!!! and none of that has to do with craftmanship - in fact it''s totally IRRELEVANT from craftmanship. If someone chooses one of those designs it can be crafted WELL or POORLY and that''s where the cutter''s quality steps in and dictates how well he executes that particular design into a functioning light performing cut diamond!

On the one hand flavor could describe the difference between a BIC and an FIC - how much fire vs brilliance a stone has... on the other hand it could describe a facet pattern. The angles of a princess might dictate how light return is affected, and the number of chevrons might influence *how* that light return is manifested.

While I am greatly relieved to hear you say that diamond beauty is not solely dependent upon light performance - I really think you missed the boat on that last analogy. An architect designs a building. Craftsmen build it. They''re different things, and yet when you look at the building if EITHER are off, the entire building is unattractive. That in no way should encourage you to mistake the execution of a design with the design itself.

 

[Cehrabehra]

Date: 11/10/2006 9:41:17 AM
Author: Paul-Antwerp

Date: 11/10/2006 7:35:29 AM
Author: oldminer

Cut Craftsmanship is partly symmetry and polish, but I include good design of the facets just like one would look at the appearance of a building to judge the quality of its architecture and not judge it by how well only the stucco was applied. There are many features of craftsmanship in diamonds that go beyond polish and symmetry. Since diamonds are costly, I really think part of craftsmanship is the creation of something beautiful, too. It is not a simple measure to grade craftsmanship, but craftsmanship alone, does not make a the entire image of a diamond.

As the decision of 2, 3, 4 or more lines of chevrons is not a decision of good or bad, and it is only a matter of taste and not performance, I see no way in which this can be graded. It can only be described.

Live long,

I totallly agree with this paul. It's a blueprint. it is a design blueprint.

 

[Cehrabehra]

Date: 11/10/2006 9:48:01 AM
Author: Rhino

Date: 11/7/2006 10:38:41 AM
Author: Cehrabehra

Date: 11/7/2006 9:29:12 AM
Author: oldminer
Paul , do you feel it would be best to grade the quality of craftmanship separately from quality or amount of light performance? Or, would you prefer the two ''grades'' to be combined?

I''m not paul, but *I* think they should be separate. ALSO I think the different numbers of chevrons should be labeled the same way I wish they''d manage cushions a bit better instead of having an endless array of cuts under one heading.

I hear ya Cehra. It''d make life a little simpler eh? Not sure if this was answered already but at least with AGS graded princess cuts the consumer can determine the number of chevrons by looking at the face-up/down graph on the AGS Reports. The face down view will show the number of chevrons. I cropped these from the AGS Reports of the 2 stones in that vid.

All the best,

hahaha - I''m willing to walk the talk of princess cuts, but really I''m in this as a cushion advocate If these standards can be set for one group of cut, they can for the rest. Cushions are the worst organized mess on the diamond market so I''m sure it will be a long time in coming... but one can hope and wait and encourage

 

[Cehrabehra]

Date: 11/10/2006 9:54:53 AM
Author: Paul-Antwerp
You are right, Rhino, I forgot about that drawing.

It is a pity, though, that AGS in their drawing is using the same size for all chevrons. It would look much better if the drawing of the 2-chevron-stone would show the true size of the facets, which is about double that of the drawing.

Live long,

I support your opinion in this 100%. Accurate facet plots to me are just as important as accurate inclusion plots.

 

[Cehrabehra]

Date: 11/10/2006 9:55:37 AM
Author: Rhino

I agree Cehra. The thing is I don''t think most folks care about the number of chevrons perse as most princess cuts on the market (including AGS Ideals) primarily consist of 3-4 chevron pavilions. The more folks get educated on the subject however and view them, only then will demand increase for one style over another. The folks we''ve showed this comparison to have been a pretty even split that I can recall. Perhaps I should hold a survey (once Tim gets back from vacation) and tally up to see where most consumer preference lies with this?

Peace,

Yeah but Jon, most folks (aka consumers) don''t care about almost *anything* we talk about here LOL!! When I got here I found it frustrating to be told right off the bat "Educate yourself!" and to quickly find that that education really was reserved for rounds. When the consumers decide to know, it should be available for them TO know. We shouldn''t just assume that because right now they don''t even know the difference between a princess and an asscher, that when they DO decide they want to know more, they shouldn''t have good access to the difference between a 2 and 4 chevron princess and what that means.

I really don''t think it matters how many chevrons the majority of consumers prefer, unless it is a purchasing issue for you. Three people out of four might prefer the look of 4 chevrons, but what about the other one? Should that mean that we keep him ignorant of what a 2 chevron looks like and just feed him the same mass produced 4 chevrons everyone else gets because more people preferred jif? I mean 4? hehe

 

[Cehrabehra]

Date: 11/10/2006 10:17:54 AM
Author: Rhino

While I agree with what you''re saying here Paul, what I believe Dave is trying to communicate is that while the number of chevrons should be noted in helping a consumer determine which flavor they like most ... the optical arrangement of those facets should be graded and taken into account.

For example there are many manufacturers of 3-4 chevron princess cuts but not all of them are cut to the same level of precision (craftsmanship) which is identifiable through scopes like the ASET and various red reflectors. This is what I believe Dave is trying to convey. Correct me if I''m wrong Dave.

Peace,

You make an excellent point jon... just using cushions (haha) as an example... I how wide or narrow the pav mains are ALSO makes a difference, as well as the LGF length on the stone. a square H&A for example will have 8 very evenly spaced mains with much longer LGF than an OMC which generally has 4 larger and 4 smaller pav mains and shorter lgf. Most would not confuse the two despite that *technically* they would both fit the same *generic* facet plot.

I do, however, still consider this to be a design issue and not an issue of execution.

 

[Cehrabehra]

Date: 11/10/2006 10:26:23 AM
Author: Rhino
How are things up around your parts? Yesterday it was actually warm here in NY and today is off to a good start too.

Peace,

don''t expect it to last... we just had a week of rain and storms and we all know which way the wind blows... ---> east!

 

[Cehrabehra]

Date: 11/10/2006 10:39:03 AM
Author: He Scores

Good morning to you Rhino...

64° and sunny today.

The other thing that I noticed about chevrons is that the larger the stone, the more likely hood of more chevrons. I am currently fixing several in the 1.5ct. range and they have four chevrons where small stones will have the two or three. From a cutting standpoint, it''s harder to put 4 on a small stone.

Bill

it might be really lovely to see 2 on a 3 carat though

 

[Cehrabehra]

Date: 11/10/2006 10:39:54 AM
Author: Rhino

I agree. Here''s the comparison of the AGS graphic as compared to an actual scan of the stone. What you say above is right on, about double the size.

okay, so WHY can''t GIA and AGS put actual scans of the stones on their certs rather than those generic facet plots which usually but don''t always accurately tell the story? (okay so the # might be accurate but not placement)

 

[oldminer]

Maybe my analogy was less effective than I had hoped. The point I was attempting to make is that we, dealers, gemologists, appraisers and informed consumers, want a system to GRADE the cut of diamonds which works well and can be reasonably understood.

Light Behavior is one part of grading and Design/Polish/Symmetry is the other part of this 2 part puzzle. I won''t argue that it might be more completely divided into three or more parts, but the present convention is one part or two parts to create a single Cut Grade.

My preference is two part grading. Everything that is not measured Light Behavior is in part #2.

Cutting a diamond is a lot different than the construction of a building. You are right in that regard. Cutting a diamond is far more an individual effort. Mass production practices divide the work among variously skilled people yet the head artisan in a cutting shop is controlling nearly every aspect.

Chevron count or faceting design makes a large difference in appearance. The person who buys a diamond makes a preferential choice about what they want to spend money on. Good designs can give a great variety of appearances yet there is little impact on cost or value. The value is altered by the perception of beauty. Maybe we can measure it, to an extent, with Light Behavior. We can certainly judge the quality of craftsmanship with measurements and careful observation under magnification.

 

[Cehrabehra]

Date: 11/10/2006 12:47:21 PM
Author: oldminer
Maybe my analogy was less effective than I had hoped. The point I was attempting to make is that we, dealers, gemologists, appraisers and informed consumers, want a system to GRADE the cut of diamonds which works well and can be reasonably understood.

Light Behavior is one part of grading and Design/Polish/Symmetry is the other part of this 2 part puzzle. I won''t argue that it might be more completely divided into three or more parts, but the present convention is one part or two parts to create a single Cut Grade.

My preference is two part grading. Everything that is not measured Light Behavior is in part #2.

Cutting a diamond is a lot different than the construction of a building. You are right in that regard. Cutting a diamond is far more an individual effort. Mass production practices divide the work among variously skilled people yet the head artisan in a cutting shop is controlling nearly every aspect.

Chevron count or faceting design makes a large difference in appearance. The person who buys a diamond makes a preferential choice about what they want to spend money on. Good designs can give a great variety of appearances yet there is little impact on cost or value. The value is altered by the perception of beauty. Maybe we can measure it, to an extent, with Light Behavior. We can certainly judge the quality of craftsmanship with measurements and careful observation under magnification.

::sigh:: well david, that certainly does help me understand your predicament for sure.... BUT I do not agree that it SHOULD be in those two parts to begin with I guess. I do understand the desire for a unified cut grade but I think it''s short sited to tuck facet plot *design* in amongst the workmanship issues. It might work for now, but design itself is such a crucial and complicated issue, I don''t see how it can last long term relegated as a tucked away part of craftmanship just because you guys aren''t really ready to deal with it. Why not set it up as its own issue and ADMIT you aren''t ready to deal with it yet? Though I can argue with myself and say that facet design plays a direct roll in cut grade. ugh. I see where the frustration comes from, but I really don''t feel I can philosophically budge from confusing design with execution. All of these factors are interrelated, I just don''t agree that your two part system will do anything to help define flavor in design.

 

[Paul-Antwerp]

Date: 11/10/2006 12:36:20 PM
Author: Cehrabehra

Date: 11/10/2006 9:55:37 AM
Author: Rhino

I agree Cehra. The thing is I don''t think most folks care about the number of chevrons perse as most princess cuts on the market (including AGS Ideals) primarily consist of 3-4 chevron pavilions. The more folks get educated on the subject however and view them, only then will demand increase for one style over another. The folks we''ve showed this comparison to have been a pretty even split that I can recall. Perhaps I should hold a survey (once Tim gets back from vacation) and tally up to see where most consumer preference lies with this?

Peace,

Yeah but Jon, most folks (aka consumers) don''t care about almost *anything* we talk about here LOL!! When I got here I found it frustrating to be told right off the bat ''Educate yourself!'' and to quickly find that that education really was reserved for rounds. When the consumers decide to know, it should be available for them TO know. We shouldn''t just assume that because right now they don''t even know the difference between a princess and an asscher, that when they DO decide they want to know more, they shouldn''t have good access to the difference between a 2 and 4 chevron princess and what that means.

As this particular post is my 1''000th post on PS, I took the time to contemplate what its subject should be. And of everything I have read here in the past days, the above highlighted sentence is a good candidate for ''observation of the year''.

We should indeed realise that most knowledge on cut and most cut-grading tools are based upon the study of round brilliants. At the same time, we should realise that a round brilliant is a rather standardised cut (with a specific faceting pattern) and with cut-quality historically centering around one specific set of proportions (Tolkowsky). As such, it is rather easy to study, but it is very dangerous to automatically apply the acquired knowledge to fancy-cuts.

As this thread shows, in princess-cuts, there is no standardised faceting-pattern, and there clearly is no historic centering-point. The same is true for other fancy shapes, but I need to add, that since we did not venture into cutting these, my knowledge of these is close to zero. May I repeat this: ''You may consider me a diamond-expert, but as an expert, I tell you that I currently know close to nothing about other cuts than round brilliants or princess-cuts.''

Because most studies concentrate on rounds, most of the tools for rounds do not necessarily work for princess-cuts. This is true for idealscope, and even a ASET-photograph gives me insufficient info. Like Jonathan mentioned, to show the difference in character between 2 and 3-line-chevrons, photographs did not suffice, and only video could show part of the difference.

Also, a machine like the Brilliancescope will have more problems with 2-line-chevron-stones, because where one has intenser, but fewer flashes, a machine tested on rounds has a higher possibility of missing these, and of thus screwing up the assessment.

All this to thank you for voicing your frustration and to celebrate my 1''000th post.

Live long,

 

[He Scores]

Date: 11/12/2006 8:24:18 AM
Author: Paul-Antwerp

Date: 11/10/2006 12:36:20 PM
Author: Cehrabehra

Date: 11/10/2006 9:55:37 AM
Author: Rhino

I agree Cehra. The thing is I don''t think most folks care about the number of chevrons perse as most princess cuts on the market (including AGS Ideals) primarily consist of 3-4 chevron pavilions. The more folks get educated on the subject however and view them, only then will demand increase for one style over another. The folks we''ve showed this comparison to have been a pretty even split that I can recall. Perhaps I should hold a survey (once Tim gets back from vacation) and tally up to see where most consumer preference lies with this?

Peace,

Yeah but Jon, most folks (aka consumers) don''t care about almost *anything* we talk about here LOL!! When I got here I found it frustrating to be told right off the bat ''Educate yourself!'' and to quickly find that that education really was reserved for rounds. When the consumers decide to know, it should be available for them TO know. We shouldn''t just assume that because right now they don''t even know the difference between a princess and an asscher, that when they DO decide they want to know more, they shouldn''t have good access to the difference between a 2 and 4 chevron princess and what that means.

As this particular post is my 1''000th post on PS, I took the time to contemplate what its subject should be. And of everything I have read here in the past days, the above highlighted sentence is a good candidate for ''observation of the year''.

We should indeed realise that most knowledge on cut and most cut-grading tools are based upon the study of round brilliants. At the same time, we should realise that a round brilliant is a rather standardised cut (with a specific faceting pattern) and with cut-quality historically centering around one specific set of proportions (Tolkowsky). As such, it is rather easy to study, but it is very dangerous to automatically apply the acquired knowledge to fancy-cuts.

As this thread shows, in princess-cuts, there is no standardised faceting-pattern, and there clearly is no historic centering-point. The same is true for other fancy shapes, but I need to add, that since we did not venture into cutting these, my knowledge of these is close to zero. May I repeat this: ''You may consider me a diamond-expert, but as an expert, I tell you that I currently know close to nothing about other cuts than round brilliants or princess-cuts.''

Because most studies concentrate on rounds, most of the tools for rounds do not necessarily work for princess-cuts. This is true for idealscope, and even a ASET-photograph gives me insufficient info. Like Jonathan mentioned, to show the difference in character between 2 and 3-line-chevrons, photographs did not suffice, and only video could show part of the difference.

Also, a machine like the Brilliancescope will have more problems with 2-line-chevron-stones, because where one has intenser, but fewer flashes, a machine tested on rounds has a higher possibility of missing these, and of thus screwing up the assessment.

All this to thank you for voicing your frustration and to celebrate my 1''000th post.

Live long,

Paul,
I admire your humbleness.

I was taught my trade by a man who specialized in fancy shapes and fancy colors. I was taught that the "beauty of a fancy shape is in the shape." To buy a fancy for brilliance is counter productive. The Brilliant is so called because it is that. The most brilliant. The more one deviates from a round the greater the loss of briliance. Straight edges are the least brilliant of all diamonds. When I say brilliant, I''m referring to the reflection of the spectral colors and a good degree of surface reflection from each individual facet. The most popular fancy would likely be a heart of a squatty oval since they lend themselves most closely to a round, but they are far from being the most popular shape. Over my 30 years in the business, the MQ was and the Princess cut now is the most popular fancy. Neither being the most brilliant of diamonds. So much for performance from the standpoint of brilliance. Their is a big difference as we have seen in how well stones like this are made. Workmanship!

This is why, the majority of diamonds cut are rounds, and this is why I agree with your statement highlighted above that assigning brilliance quantification to fancies is erroneous. However, as I pointed out, the making of all diamonds from the cutter''s workmanship by placing one facet on at a time is VERY SIMILAR and in most cases has measurable results that can be evaluated for accuracy.

The complications that arise however are that which of the elements of this facet making are more important than others. One has to be able to separate characteristics of the stone which are individual taste, or are a result of the facet making process rather than facet evaluation in itself.

Bill Bray
Diamond Cutter