Low LGF%? Need advice on this stone

[Cehrabehra]

Date: 7/18/2007 6:00:07 PM
Author: belle

Date: 7/18/2007 5:54:41 PM
Author: Cehrabehra

Date: 7/18/2007 5:52:10 PM
Author: belle

Date: 7/18/2007 5:49:01 PM
Author: Cehrabehra

Date: 7/18/2007 5:46:13 PM
Author: belle

Date: 7/18/2007 5:40:39 PM
Author: Cehrabehra

you know what the cow saw in the parallel universe? Lots of beans, lots of beans, lots of beans, lots of beans.

lmao....

where is he now? where is the cow?

that reigned supreme here until we found the mango one in my avatar - omg my kids were just singing that today - not a day goes by without a mango reference LOL Oh, except they DO talk about a magical toe, starting to glow LOL

*gasp* better than trevor??

YES! once upon a time....

....better than a llama?

yes! and even better than a badger (but just barely)

 

[whatmeworry]

Date: 7/18/2007 5:54:00 PM
Author: Maisie

Date: 7/18/2007 5:42:39 PM
Author: JohnQuixote

Date: 7/18/2007 5:38:17 PM
Author: Cehrabehra

don''t stay out of it silly woman!!! Its kinda like this:

a meatloaf with a 1 1/2 tsp of thyme and 1/2 tsp of oregano will be just as good as a meatloaf with a 1/2 tsp thyme and 1 1/2 tsp oregano. But to the trained palate they will be able to tell the difference between the two and might even argue over which is best (with some saying the sweet spot is 1 tsp of each lol) but both meatloaves are yummy and awesome and some people wouldn''t even tell the difference. And some would start breaking it up into quarter teaspoons or saying no no no its not about the balance between thyme and oregano, it''s about the basil!! And then you have 3 components to the recipe (formula). As long as you''re not putting a pound of herb with 1/2 pound of meat, you should be okay... you know, as long as you have some flavoring to your meat, the actual amounts are debatable. And debate is just what some like to do here. Its just important to know when the debate is over how many teaspoons of flavor you''re adding (and sometimes too much flavor isn''t good!) vs how fresh the meat is or something truly important.

And some people are going to pour catsup all over ''em anyway! Ever seen a grown chef cry?

Masie, stay with us.

Just keep it reeeal.

No thanks love! I shall just stick with trusting the experts to choose for me. I am not technically minded but thats ok. I don''t really mind that I don''t understand the in''s and out''s of a diamond. I''m an expert at wearing one - thats all that matters to me!!

. Bravo!

 

[michaelgem]

Michael,

Can you please just post the relevant parts of of your articles that pertain to the discussion at hand and without references to pictures not included. I do not wish to leave Pricescope to go look at a long article that may have only a small portion relevant to the discussion.

Also, who are the number of individuals and diamond manufacturers that you quote as agreeing with you, as those of us who may or may not agree with you would like to know. In this instance I concord that the center of the range is 77.5%, but strongly dissagree that 75% is as low as one should go. If you are going to claim that you are in the mainstream then please pay us the courtesy of disclosing who the mainstream is.

Wink

Wink,

What is the point of declaring you strongly dissagree that 75% is as low as one should go? That is not at all what my article says. I am earnestly trying to explain the common areas of agreement in the diamond community between AGS, GIA, Ideal diamond cutters, both past and present, and gemologists, myself included.

WRT lower half length, you are welcome to strongly disagree that 75% is as low as one should go. You would be in agreement with both GIA and AGS. The accordance that I point out in lower half length and all the 7 dimensions is the center, not the range of the sweet spot. However, I'd bet if you can get most super ideal manufacturers to comment, you would learn that their lower half length is between 75% and 80%. BTW I have verified this with measurements of several super ideal cut diamonds.

I can't help it if you are unwilling to tear yourself away from Pricescope long enough to read what I have to say. That implies you don't think it worth the effort. I have posted the small portions relevant to the discussion, and some may think even those were too long. Complex concepts need careful exposition, which makes for the necessary length of this article. In the end I reduce the complexity to conculsions that are simple if viewed in light of the exposition. I encourage you to check it out.

As far as naming those in agreement with the articles conclusions, they vary slightly depending on the specific dimension. The two biggies that the article points out are in agreement in all the dimensions that I was able to determine were GIA and AGS. The centers of the two dimensions of lower half length and star length for AGS are not addressed. They don't state any limits on these parameters, relying instead on the asset tool and dispersion metrics in the PGS software to call the performance grade.

The article references as examples, two super ideal cutters, one from Belgium and one from South Africa, one well known to AGS and both highly respected. I've talked to many others as well. For my investigations and photography, I retain example super ideals from most of the major players, which I have analyzed for verification including for example, HOF, ACA, EightStar, LK, ISEE2, various AGS000s and GIA triple EXs.

Ideal regards,

Michael

 

[WinkHPD]

Date: 7/18/2007 7:32:38 PM
Author: michaelgem

Michael,

Can you please just post the relevant parts of of your articles that pertain to the discussion at hand and without references to pictures not included. I do not wish to leave Pricescope to go look at a long article that may have only a small portion relevant to the discussion.

Also, who are the number of individuals and diamond manufacturers that you quote as agreeing with you, as those of us who may or may not agree with you would like to know. In this instance I concord that the center of the range is 77.5%, but strongly dissagree that 75% is as low as one should go. If you are going to claim that you are in the mainstream then please pay us the courtesy of disclosing who the mainstream is.

Wink

Wink,

What is the point of declaring you strongly dissagree that 75% is as low as one should go? That is not at all what my article says. I am earnestly trying to explain the common areas of agreement in the diamond community between AGS, GIA, Ideal diamond cutters, both past and present, and gemologists, myself included. You stated that 75% was your low end, stating a personal preference as if it were a fact. My point is that it is a preference and that both GIA and AGS have found that stones with lower LGF''s deserve the AGS 0 grade if all other factors are also correct.

WRT lower half length, you are welcome to strongly disagree that 75% is as low as one should go. You would be in agreement with both GIA and AGS. The accordance that I point out in lower half length and all the 7 dimensions is the center, not the range of the sweet spot. However, I''d bet if you can get most super ideal manufacturers to comment, you would learn that their lower half length is between 75% and 80%. BTW I have verified this with measurements of several super ideal cut diamonds.

I can''t help it if you are unwilling to tear yourself away from Pricescope long enough to read what I have to say. That implies you don''t think it worth the effort. I have posted the small portions relevant to the discussion, and some may think even those were too long. Complex concepts need careful exposition, which makes for the necessary length of this article. In the end I reduce the complexity to conculsions that are simple if viewed in light of the exposition. I encourage you to check it out. I have many of your articles, and stayed up half the night to discuss them with you at the EightStar convention we were at together. I find your articles frequently interesting whether I agree with them or not. However, I find your constant attempts in post after post after post to drive us to read your article to be distracting to the conversation and believe it better to post the relevant parts here, where it will always be searchable and available to us.

As far as naming those in agreement with the articles conclusions, they vary slightly depending on the specific dimension. The two biggies that the article points out are in agreement in all the dimensions that I was able to determine were GIA and AGS. The centers of the two dimensions of lower half length and star length for AGS are not addressed. They don''t state any limits on these parameters, relying instead on the asset tool and dispersion metrics in the PGS software to call the performance grade.

The article references as examples, two super ideal cutters, one from Belgium and one from South Africa, one well known to AGS and both highly respected. I''ve talked to many others as well. For my investigations and photography, I retain example super ideals from most of the major players, which I have analyzed for verification including for example, HOF, ACA, EightStar, LK, ISEE2, various AGS000s and GIA triple EXs. Fine, and when quoting numerous players and not naming them you loose some credibility with those of us who like full attribution if we are to credit the information. When you coordinate with another and want us to believe that they are in accordance with your statement, then please do us the honor of naming them. You normally footnote your articles, at least the ones that I have read, so if you are making such a statement here, please include the names.

Ideal regards,

Michael

Just my feelings and comments.

Wink

 

[michaelgem]

Just my feelings and comments.

Wink

You are having a grumpy day.

No sense in my responding.

 

[michaelgem]

Date: 7/18/2007 5:02:55 PM
Author: Garry H (Cut Nut)

Date: 7/18/2007 11:16:32 AM
Author: Paul-Antwerp
Michael,

On a totally different point.

The concept of a ''sweet spot'' being in the center of a lab''s top-range is for me contrary to the original article of Bruce Harding, where top-performers are always close to an area where performance suddenly drops.

Is there any proof that Mount Everest is at the center of the Himalaya-range?

Live long,

Precisely the question (never answered) that I asked michael here https://www.pricescope.com/community/threads/41-degree-pavillion-angle.65301/page-4 about 1/3rd of the way down the concurrent 41 degree pavilion thread.

GIA''s research indicates that optimum light return is not in the center of the isobars (what are the height thingy''s on graphs?)

Garry, this question is answered before you made this post and on the same page.

I also answered the same question on the same page 4 in the 41 degree thread above your post there as well.

Check it out.

Michael

 

[pyramid]

off topic but Michaelgem, in the other thread you gave your advice on about the 41 pavillion, 34 crown diamond I have bought, I wanted to ask you a question. I know what you are saying about the performance of the stone and that this crown height is required for this pavillion angle, I was just wondering though in all the studying that is done about these diamonds in the 7 dimensions, do you ever consider anything about the view asthetically from the profile? Does the 34 crown being lower than 34.5 or 34.8 get considered in what makes a ideal diamond or is it just strictly to do with the performance of the light return?

 

[aljdewey]

Date: 7/18/2007 11:00:15 AM
Author: JohnQuixote

It''s true that someone big causes more obstruction. Hey, as long as we''re at it maybe we can develop a height-weight reference chart for lower halves %? We could even have different cutouts in our showrooms...

''Excuse me sir, I think this diamond suits you better.''
''But I like that other one.''
''No no. You''re in the welterweight division, I''m afraid you''re restricted to these...''

Please - PLEASE - don''t even suggest it in jest.

Because if you do, I can almost guarantee that the next flap on PS is gonna be whether or not you should buy a given stone based on your height.

 

[aljdewey]

Date: 7/18/2007 5:46:13 PM
Author: belle

Date: 7/18/2007 5:40:39 PM
Author: Cehrabehra

you know what the cow saw in the parallel universe? Lots of beans, lots of beans, lots of beans, lots of beans.

lmao....

where is he now? where is the cow?

Ok - first prize goes to the person who can correctly identify the optimal AGS0 cow.

Runner up gets to taste the meatloaf when the cow is no longer a cow!

 

[aljdewey]

Date: 7/18/2007 5:36:31 PM
Author: Wink

I think you are more likely to get a good clear in focus picture of bigfoot in the wild than you are to find an ugly AGS 0.

AHAHHAHAHAHHhhhhhhhhhaaaaaaaaaaaa

Wink, when Rich grows tired of me, will you marry me??!!

I''m fairly good at photography, so I think I can sport that bigfoot pic for ya!

 

[WorkingHardforSmallRewards]

Date: 7/18/2007 9:06:17 PM
Author: aljdewey

Date: 7/18/2007 11:00:15 AM

Author: JohnQuixote


It''s true that someone big causes more obstruction. Hey, as long as we''re at it maybe we can develop a height-weight reference chart for lower halves %? We could even have different cutouts in our showrooms...


''Excuse me sir, I think this diamond suits you better.''

''But I like that other one.''

''No no. You''re in the welterweight division, I''m afraid you''re restricted to these...''

I am afraid that wouldn''t be sufficient. My gf is very small and skinny, about 93 pounds I think...and she has a massive head Its not always noticeable except in pictures, but I think the head obstruction would probably be in that aforementioned welterweight division. Thus, while I am def a supporter of this concept (in so much as recommendations are concerned at least

lol) I think we might should move back to those little metal-clamp head measuring devices? maybe that would be more accurate.

 

[strmrdr]

Date: 7/18/2007 3:55:04 PM
Author: Wink

Date: 7/18/2007 3:40:39 PM
Author: Maisie

Date: 7/18/2007 1:22:50 PM
Author: strmrdr

Date: 7/18/2007 1:13:24 PM
Author: Wink
An AGS 0 will be a beautiful stone, it may come in several flavors, but it will be beautiful.

Wink

That''s real hard claim to prove without having seen em all.
Your seeing some of the best AGS0''s from Paul.
How many of the worst combo(which ever that is) none symmetrical ags0''s have you seen?

So an AGS0 could also be a yuk? I thought that the AGS0 would always be a great stone to have? The price seems to imply this.

Maise,

I reiterate, I HAVE NEVER SEEN ONE!

I suppose it is theoretically possible, but I have NEVER SEEN ONE!

Dang it Storm, See what you''ve done.

You rang?
I get yelled at for talking in absolutes and I get yelled at for pointing out the person yelling at me is doing the same.

You do realise that some very bright minds are working on how to game the cut grades right now and show others how too.
No Paul isnt going to cut them and Brian, Jon and other trusted vendors arent going too sell them but they will sure as shooting be out there just like they were for the original AGS cut grade. Its going to be much harder this time around and the GIA system is much easier to game so who knows how many will bother too do so but if the $$ is there some will.

anyway,,,, Im going to let it go as you having a bad day and forgive ya. :}

 

[strmrdr]

Date: 7/18/2007 10:41:04 PM
Author: WorkingHardforSmallRewards



I am afraid that wouldn''t be sufficient. My gf is very small and skinny, about 93 pounds I think...and she has a massive head Its not always noticeable except in pictures, but I think the head obstruction would probably be in that aforementioned welterweight division. Thus, while I am def a supporter of this concept (in so much as recommendations are concerned at least

lol) I think we might should move back to those little metal-clamp head measuring devices? maybe that would be more accurate.

That''s what the picture is for along with the 27 questions in my joking post above.
ROFL!!!

 

[Regular Guy]

A few miscellaneous points, culled from where?

- JohnQ, thanks for giving recently a rationale for trusting percent data on pavillons, when offered.
- I would say that advice is "spot on..." or is it Spock on? (damn...where's that "strike-through" when I need it!
- adding on to Storm's note, mostly really with some curiosity...

Date: 7/18/2007 1:27:29 PM
Author: strmrdr

Date: 7/18/2007 1:21:03 PM
Author: Paul-Antwerp
A complete side-note, but all Infinity-rounds have a HCA-score close to 0.5
Live long,

huh? at one time that was true when you were cutting a lot of shallower pavilion stones but I just searched your website and all the ones I looked at would score in the 1 range....

The several I saw recently when wanting to ferret out Infinity's pattern of cutting came with AGS certs, but the older kind. Is this an instance of, again, the Princess Bride acting up? (Boy, that got a rise last time...but different context now.)

BTW...I'm late to this party (though hopefully not ending it)...and am clearly a slow learner. The minor facets have not joined my lexicon.

 

[echelon6]

Michael,

I read the article you linked to a while back last night and I didn''t find much explanation on why the LGF sweetspot is at 77.5% except that you mentioned that several groups and experts all agree?

I was thinking exactly on the same line as the Everest - Himalayan example. The ideal LGF answer being the arithmetic midpoint only applies if performance varies linearly with LGF. But as with many things, linear relationships are somewhat rare in real life, so at the moment without further explanation, the LGF midpoint theory doesn''t seem logical to me.

Could you please elaborate?

 

[echelon6]

To Storm and everyone else:

Since LGFs are cut AFTER the MPF''s (citing Paul), then shouldn''t the LGF angles be LESS THAN the MPF angles? (See my diagram)

Yet, according to Storm''s Diamcalc data, a MPF of 40.75 equates to an LGF angle of 41.84? (see a couple of pages back, Storm you remember this?)

This got me thinking hard for a while, and I conclude I''m missing something here...

a>b QED:

 

[Cehrabehra]

Date: 7/19/2007 2:20:48 AM
Author: echelon6
To Storm and everyone else:

Since LGFs are cut AFTER the MPF''s (citing Paul), then shouldn''t the LGF angles be LESS THAN the MPF angles? (See my diagram)

Yet, according to Storm''s Diamcalc data, a MPF of 40.75 equates to an LGF angle of 41.84? (see a couple of pages back, Storm you remember this?)

This got me thinking hard for a while, and I conclude I''m missing something here...

a>b QED:

love the pic Problem is you have switched the places.... the mains are the 8 lower ones that look like a star.... the LGF are the upper ones on the pavillion... the lower GIRDLE facets - meaning below the girdle. They''re not actually the lower facets on the stone Upper girdle facets are on the crown and they''re the lowest ones, closest to the girdle. Then the kite/bezel then the stars, then the table.

 

[diagem]

Date: 7/19/2007 2:20:48 AM
Author: echelon6
To Storm and everyone else:

Since LGFs are cut AFTER the MPF's (citing Paul), then shouldn't the LGF angles be LESS THAN the MPF angles? (See my diagram)

Yet, according to Storm's Diamcalc data, a MPF of 40.75 equates to an LGF angle of 41.84? (see a couple of pages back, Storm you remember this?)

This got me thinking hard for a while, and I conclude I'm missing something here...

a>b QED:

Your sketch is wrong..., remeber its called lower girdle facets!!!
Your sketch shows a shallower step actually not a facet that reaches the girdle.
To polish a facet on the MPF while at the same time reaching the girdle without over-running the whole MPF = (means) the LGF needs to be steeper!!!

I hope you understand what I am trying to relay!

I an confused in regards to your "citing Paul"
I read Paul's post on the first or second page (of this thread) and understood a different quote of his..., maybe he will explain...

Date: 7/15/2007 12:09:07 PM
Author: Paul-Antwerp

"If you consider that nowadays many cutters cut the LGF first and the main pavilion facets afterwards, it might lead you to think differently again."

????

 

[Cehrabehra]

Date: 7/19/2007 3:48:15 AM
Author: DiaGem

Date: 7/19/2007 2:20:48 AM
Author: echelon6
To Storm and everyone else:

Since LGFs are cut AFTER the MPF's (citing Paul), then shouldn't the LGF angles be LESS THAN the MPF angles? (See my diagram)

Yet, according to Storm's Diamcalc data, a MPF of 40.75 equates to an LGF angle of 41.84? (see a couple of pages back, Storm you remember this?)

This got me thinking hard for a while, and I conclude I'm missing something here...

a>b QED:

Your sketch is wrong..., remeber its called lower girdle facets!!!
Your sketch shows a shallower step actually not a facet that reaches the girdle.
To polish a facet on the MPF while at the same time reaching the girdle without over-running the whole MPF = (means) the LGF needs to be steeper!!!

I hope you understand what I am trying to relay!

I an confused in regards to your 'citing Paul'
I read Paul's post on the first or second page (of this thread) and understood a different quote of his..., maybe he will explain...

Date: 7/15/2007 12:09:07 PM
Author: Paul-Antwerp

'If you consider that nowadays many cutters cut the LGF first and the main pavilion facets afterwards, it might lead you to think differently again.'



????

he's citing paul for saying that the lower girdles are cut AFTER the pavillion mains.... but in his drawing he has switched the places of the lgf and the mains. I think the term "lower" might have thrown him. Oh, I see you've added more since I read your post LOL I always understood the 8 mains to be cut first but maybe paul will come back.... oh and by first I don't mean *first* I just mean first on the pavillion.

 

[Garry H (Cut Nut)]

It is not uncommon these days (I am told) to cut the LGF first

 

[echelon6]

Ahhh yes yes I stand corrected. Everything makes sense now geometrically.

 

[diagem]

Date: 7/19/2007 8:28:58 AM
Author: Garry H (Cut Nut)
It is not uncommon these days (I am told) to cut the LGF first

In automation cutting machines...
I never heard of "human" cutters doing it...

 

[strmrdr]

Date: 7/19/2007 8:45:16 AM
Author: echelon6
Ahhh yes yes I stand corrected. Everything makes sense now geometrically.

from here: http://www.goodoldgold.com/Articles/MinorFacets/

 

[michaelgem]

echelon6 says:

I read the article you linked to a while back last night and I didn''t find much explanation on why the LGF sweet spot is at 77.5% except that you mentioned that several groups and experts all agree?

I was thinking exactly on the same line as the Everest - Himalayan example. The ideal LGF answer being the arithmetic midpoint only applies if performance varies linearly with LGF. But as with many things, linear relationships are somewhat rare in real life, so at the moment without further explanation, the LGF midpoint theory doesn''t seem logical to me.

Could you please elaborate? echelon6

Sure

echelon6 and others are misreading me thinking that I am saying that the sweet spot center is where the Everest peak is located. Use of the sweet spot analogy says that within this range or area there is no peak. It is by its definition, an area of top, but equal performance, like a plateau at the top of the mountain rather than a peak.

Those who favor teaching scientific ideas using analogies should gravitate to the sweet spot concept, which is a sports analogy.

For example, the ''sweet spot'' in tennis is the area in the head of a racket where the ball is struck with maximum control and speed. Striking the ball within the sweet spot causes it to respond with the best, most consistent performance. Oversize rackets dominate the game today, because of their larger sweet spot area. The tennis player aims to hit the center of this area, so even when he is off a little he gets the same performance as long as the ball hits within the sweet spot.

In analogous fashion, there is a ''sweet spot'' range in terms of cutting angles and proportions for peak diamond performance. The range of this sweet spot encompasses pavilion and crown angles long associated with the ''Ideal'' cut such as those of Morse and Tolkowsky. In this sense, the range of angles and proportions said by GIA and AGS to give the best brilliance, fire and sparkle, are their respective sweet spots.

When the cutter fashions the diamond with sufficient craftsmanship to obtain a diamond within the sweet spot range, the diamond responds with the best light performance and beauty.

I observe that both GIA and AGS have almost identical centers to their respective sweet spots for table %, pavilion and crown angle (56%, 41 and 34 degrees.) I am not saying that the center is any better than any other point within the sweet spot. Just the opposite. For example, AGS gives the same Ideal 0 grade to all points within their sweet spot, so this area, by AGS definition, looks like a plateau at the top of the performance mountain, not a peak.

Purists, like Paul, Wink, Strmrdr, John, Brian, Bill, Jonathan, myself and many others on this forum, are like eagles swooping down on this plateau and noticing that it really is only flat to the casual observer who does not notice the details in the landscape that we see.

We see the plateau of pavilion/crown angle combinations as a somewhat bumpy terrain that does have somewhat of a ridge along what I have referred to as the “Axis of Ideal”. That inverse sloping ridge is important for us purists, as you can tell by Garry’s, my and others writing. However, as long as the cut parameters remain in the sweet spot, by its very definition, for example, of AGS Ideal 0, the typical observer of this top graded diamond, in most typical lighting, will not likely notice these subtle performance differences.

Let me post this, as it is too long for a sound bite, and I will address echelon6’s pavilion half length question next.

Ideal regards,

Michael

 

[WinkHPD]

Date: 7/19/2007 10:45:35 AM
Author: michaelgem

echelon6 says:

I read the article you linked to a while back last night and I didn''t find much explanation on why the LGF sweet spot is at 77.5% except that you mentioned that several groups and experts all agree?

I was thinking exactly on the same line as the Everest - Himalayan example. The ideal LGF answer being the arithmetic midpoint only applies if performance varies linearly with LGF. But as with many things, linear relationships are somewhat rare in real life, so at the moment without further explanation, the LGF midpoint theory doesn''t seem logical to me.

Could you please elaborate? echelon6

Sure

echelon6 and others are misreading me thinking that I am saying that the sweet spot center is where the Everest peak is located. Use of the sweet spot analogy says that within this range or area there is no peak. It is by its definition, an area of top, but equal performance, like a plateau at the top of the mountain rather than a peak.

Those who favor teaching scientific ideas using analogies should gravitate to the sweet spot concept, which is a sports analogy.

For example, the ''sweet spot'' in tennis is the area in the head of a racket where the ball is struck with maximum control and speed. Striking the ball within the sweet spot causes it to respond with the best, most consistent performance. Oversize rackets dominate the game today, because of their larger sweet spot area. The tennis player aims to hit the center of this area, so even when he is off a little he gets the same performance as long as the ball hits within the sweet spot.

In analogous fashion, there is a ''sweet spot'' range in terms of cutting angles and proportions for peak diamond performance. The range of this sweet spot encompasses pavilion and crown angles long associated with the ''Ideal'' cut such as those of Morse and Tolkowsky. In this sense, the range of angles and proportions said by GIA and AGS to give the best brilliance, fire and sparkle, are their respective sweet spots.

When the cutter fashions the diamond with sufficient craftsmanship to obtain a diamond within the sweet spot range, the diamond responds with the best light performance and beauty.

I observe that both GIA and AGS have almost identical centers to their respective sweet spots for table %, pavilion and crown angle (56%, 41 and 34 degrees.) I am not saying that the center is any better than any other point within the sweet spot. Just the opposite. For example, AGS gives the same Ideal 0 grade to all points within their sweet spot, so this area, by AGS definition, looks like a plateau at the top of the performance mountain, not a peak.

Purists, like Paul, Wink, Strmrdr, John, Brian, Bill, Jonathan, myself and many others on this forum, are like eagles swooping down on this plateau and noticing that it really is only flat to the casual observer who does not notice the details in the landscape that we see.

We see the plateau of pavilion/crown angle combinations as a somewhat bumpy terrain that does have somewhat of a ridge along what I have referred to as the “Axis of Ideal”. That inverse sloping ridge is important for us purists, as you can tell by Garry’s, my and others writing. However, as long as the cut parameters remain in the sweet spot, by its very definition, for example, of AGS Ideal 0, the typical observer of this top graded diamond, in most typical lighting, will not likely notice these subtle performance differences.

Let me post this, as it is too long for a sound bite, and I will address echelon6’s pavilion half length question next.

Ideal regards,

Michael

Ahhh, now THERE''s an answer I can sink my teeth into. Thanks.

Wink, in the cool of the morning. AC is still broke, so all bets are off for the afternoon.

 

[pyramid]

I think the thing that is confusing in some ways although I can see what Michaelgem means about it being an area at the top where all on it are ideal but some are nearer the centre with nuances only experts can see as being different. The thing is my stone is this centre of the sweet spot and as others here know a diamond with its proportions 34/41 56 does not get the 4 Excellents on the HCA. Now Michaelgem says experts see these nuances, including Garry, so maybe they cannot be put into words but if they were better why is the centre of the sweetspot only going to get EX, VG, VG, VG. I know that Garry's HCA may be a different thing mathematically or scientifically that I don't understand but if these nuances are better why is the Excellents not there. It is in a way saying they are all ideal, but there are different excellents. The HCA sees them in a different place from the nuances the experts are seeing. If it is the centre of the sweetspot why is the fire etc. not excellent but very good, but then that also goes with what Michaelgem said that the centre is not better the whole sweetspot is ideal for all in it.

 

[strmrdr]

Date: 7/19/2007 11:03:22 AM
Author: Pyramid
I think the thing that is confusing in some ways although I can see what Michaelgem means about it being an area at the top where all on it are ideal but some are nearer the centre with nuances only experts can see as being different. The thing is my stone is this centre of the sweet spot and as others here know a diamond with its proportions 34/41 56 does not get the 4 Excellents on the HCA. Now Michaelgem says experts see these nuances, including Garry, so maybe they cannot be put into words but if they were better why is the centre of the sweetspot only going to get EX, VG, VG, VG. I know that Garry''s HCA may be a different thing mathematically or scientifically that I don''t understand but if these nuances are better why is the Excellents not there. It is in a way saying they are all ideal, but there are different excellents. The HCA sees them in a different place from the nuances the experts are seeing. If it is the centre of the sweetspot why is the fire etc. not excellent but very good, but then that also goes with what Michaelgem said that the centre is not better the whole sweetspot is ideal for all in it.

The hca doesn''t consider the minor facets therefor the EX VG VG VG is meaningless because the lgf% in particular can change it dramatically.
Tech has moved on since the hca was written.
Its still useful for weeding out the really bad c/p combos but that''s about it.

 

[Cehrabehra]

Date: 7/19/2007 10:55:41 AM
Author: Wink


Ahhh, now THERE''s an answer I can sink my teeth into. Thanks.

Wink, in the cool of the morning. AC is still broke, so all bets are off for the afternoon.

awww wink that sucks... :::Uploading ice cold drinks::: :::banning hot tub discussions:::

 

[pyramid]

Okay thanks Storm. So the nuances that experts see are things the normal person like myself wouldn''t but what are they, like a bit more sparkle, a bit more clearness, a better balance of some minute thing, or maybe it cannot be put into words and can only be seen by those who can, in the same way cutters see things others can''t from their artistic or experience nature.

 

[strmrdr]

Date: 7/19/2007 11:24:23 AM
Author: Pyramid
Okay thanks Storm. So the nuances that experts see are things the normal person like myself wouldn't but what are they, like a bit more sparkle, a bit more clearness, a better balance of some minute thing, or maybe it cannot be put into words and can only be seen by those who can, in the same way cutters see things others can't from their artistic or experience nature.

I get into arguments with some of the experts on that all the time.
I think a lot of consumers can see the differences, I can, but some cant.
Knowing what too look for is a large part of that and I think with a little training a lot more would see the differences.
The question becomes when do the differences matter.
That is the heart of the issue.
There is no question that different lgf% give a different look the argument is at what point does it become a performance issue rather than a personality difference.
Then is becomes which personality is best.