To Sergey, all Cut Nuts, etc: A reply from ImaGem

[strmrdr]

michaelgem


WF will readily admit that they leave some direct light white light return behind for what they see as a better balanced diamond.
They could lenthen the lgf out and pick up some direct light return but they feel it would comprimise the balance of their diamonds.
They score generaly h,vh,h on the b-scope.

The gog classics go for white light return and score
vh,vh,h on the b-scope by virtue of very strong direct light return ability.

The differences between the camps reaches holy war fighting status from time to time around here over which is the best way.

8* goes for broad flashes of fire and scores about the same as the ACA on the b-scope but by different means. With totaly different looking pictures.

the cut by infinity in general from the few examples iv seen b-scope scores for will be in the vh,vh,h range and do it in a totaly different way than the GOG classic by generating a ton of small intense flashes of fire and white light.

Each camp feels they have the best formula and each cuts for a different look.
Which is best?
Which ever one preferes the look of.

I could type out a list of how they look different in indirect light where the differences are even larger than in direct light but i think my point is made.
But at the end of the day all are "ideal"

edit> no problem on the terms I just didnt want anyone getting confused. There are a lot of people reading this forum.

 

[JohnQuixote]

Date: 8/21/2005 10:41:03 PM
Author: michaelgem



I am willing to bet that ACA, Infinity, 8* and GOG will make the case that they have not compromised any of the performance attributes of beauty - brilliance, fire or sparkle in cutting their diamonds. And it is in that sense that they could claim to be ideal or if that is no longer politically correct, best.

Michael Cowing

Michael, you are correct.

Brian Gavin, Paul Slegers and Richard VonSternberg have dedicated their lives to arriving at the very specific proportions sets/cutting styles for the diamonds that are their respective brands, ACA, Infinity and Eightstar. I have seen many examples of all three cuts. All are distinctive and fabulous, with no compromise of brilliance, fire or sparkle as you say. They are all paramount. There may be slight nuances of performance and character - particularly in different lighting conditions - but those are due to different specific philosophies.

GOG does not actually cut. Rhino sources different diamonds from his supplier(s), therefore he may stock a variety of looks - and has an array of equipment to help communicate how each piece may appear. The positive there is that he has the ability to stock items with different looks. I'm sure Strm can clarify his favorite combos (what I assume he meant by 'classic' GOG).

The point being that to discriminate between what is most 'ideal' or what is 'best' must be a matter of direct assessment with such slight nuance involved, since it will be a matter of human perception and taste and not a matter of 'VH' (or whatever) versus 'H.'

 

[JohnQuixote]

Date: 8/21/2005 11:08:54 PM
Author: strmrdr

WF will readily admit that they leave some direct light white light return behind for what they see as a better balanced diamond.
They could lenthen the lgf out and pick up some direct light return but they feel it would comprimise the balance of their diamonds.
They score generaly h,vh,h on the b-scope.

Hey Strm, I don’t know where you got that info on A Cut Above and BS results, but it’s incorrect. We had BS for over a year with the old software and most were vh vh h, with some trip vh mixed in. Where did you hear that?

Rockdoc runs ACAs on his BS with the new software and can verify how they score. Feel free to ask him.

As for ‘leaving some direct white light return behind,’ that observation applies more to the Brilliancescope metric than to a real world environment – that nuance is very slight because all high end diamonds with optimum light return and great contrast look like firecrackers in direct light… It’s soft lighting where we have observed that the difs become the most notable, thus Brian's commitment to the thicker pavilion main design for ACA -which Eightstar takes farther- (here is the post where these observations were made).

Since it is topical - Whiteflash has tested mechanized light performance devices but we have not (to date) been satisfied that the results are meaningful/repeatable. We recognize the marketing value of a device like Brilliancescope that could help us sell diamonds, but Brian has not been quick to adopt something developed away from a proven lab environment b/c of the controversy. Still, as you have voiced objectively, these devices have their uses as 'part of the puzzle.'

As technology moves forward we see demand from a growing segment of the consumer population for SOME type of assessment along these lines. Therefore this thread is of great interest to us. The popularity of BS combined with the apparent repeatability of Imagem - if no bias towards certain configurations - would be a nice package for our customers who seek such feedback. So...there will come a day when we may adopt such a device. Until that time we endorse only the same natural assessment techniques used by the world’s leading laboratories.

Of course we do not feel mechanized assessment or computer simulation should ever be promoted over human perception!

Date: 8/21/2005 11:08:54 PM
Author: strmrdr
michaelgem

Each camp feels they have the best formula and each cuts for a different look.
Which is best?
Which ever one preferes the look of.

I could type out a list of how they look different in indirect light where the differences are even larger than in direct light but i think my point is made.
But at the end of the day all are 'ideal'

Precisely.

Another reason that we feel human perception is key.

 

[strmrdr]

John,

Leaving the accuracy of the b-scope and the aca reading aside for a second:
I think we can agree that each of the mentioned cuts has its own look and personality.
I think we can agree that there are some tradeoffs when picking how to cut a diamond: long lgf, vs short, girdle facets cut for return vs cut for contrast, crown and pavilion angle combos.
Each cutter/brand has its own formula that they feel is better but at the end of the day dispite looking different all the above mentioned diamonds are all top end diamonds!

When you say it comes down to "it will be a matter of human perception and taste" is exackly my point.
Using one machine and one light envirement to test diamonds DOES NOT WORK!

I dont know how to apply the test results from the imagem machine and where they fit into the tool chain therefor it does not go on MY tool chain.
Thats the bottom line.

 

[strmrdr]

John,

b-scope and white light results:
You responce again proves my point that using one machine and lighting envirement is a bad way to pick the best diamond.

Iv got to get going but one question:
Longer lgf increase b-scope white light scores and real world white light return.
True or false? and explain

There are some tradeoffs for doing so as we are well aware so if possible dont reignite the War. :}

 

[strmrdr]

I want to make it perfectly clear again that im not saying any of the diamonds I listed are not top of the line diamonds.
They will look different from one another depending on the lighting environment and some people may prefer the personality of one over the other.
Others may fall in love with the first of the group they see and need to look no further.
I am confident that when viewing them side by side in a variety of lighting conditions that just about anyone could tell them apart from one another.

To repeat myself for the hundreth time: relying on any one test to determin which diamond to buy is not seeing the entire picture and could lead to mistakes.
I do not have but have requested many times the information I need to see where imagem fits into the picture. End of story.

 

[oldminer]

I think I finally get something Strmrdr is asking about.

The ImaGem method does give an overall final grade that we would wish to say selects the best looking diamonds. We agree they would not all look identical, but they''d all look very pretty. Strmrdr is concerned with using such general findings when picking a diamond that needs to have exactly the right "look". ImaGem provides that tighter process for consumers or dealers.

However, Strmrdr and others reading the thread may not know there are individual readings, repeatable numberical ones, given by ImaGem, that provide Brilliance, Sparkle and Intensity separately. If one has two diamonds which get highly similar results in each of the three characteristics mentioned, then those diamonds will very likely look much the same.

If one wanted to buy a Branded diamond sight unseen and had ImaGem''s output data on other diamonds of that Brand, there would be fairly tight clusters of related readings, and one could have a degree of assusrance that an unseen stone, within those reading clusters, also looked very similar. This assumes the cutter of the Brand makes their diamonds cut to very tight tolerances. A few Brands are in name only, while most others are very tightly controlled by cut parameters to keep their look consistent.

Does this respond more to the point of your argument?

 

[JohnQuixote]

Date: 8/22/2005 9:10:59 AM
Author: strmrdr
John,

b-scope and white light results:
You responce again proves my point that using one machine and lighting envirement is a bad way to pick the best diamond.

Iv got to get going but one question:
Longer lgf increase b-scope white light scores and real world white light return.
True or false? and explain

There are some tradeoffs for doing so as we are well aware so if possible dont reignite the War. :}

Answer: Longer lgf improve BS scores but not exclusively the white light score. The scint score is influenced for the same fundamental reason: Thinner pavilion mains = more narrow/intense return when bombarded with photons. You said in another thread "How a diamond looks in a box is worthless because no one carries diamonds around in a box saying here put your eyeball 2.2 cm from this and see the awesome diamond." That was in a different context, but is a good summation of what’s going on here. In a tiny box bombarded with photons the differences in bias we're discussing are exaggerated. In real world conditions the direct light you get doesn't exaggerate them.

We're angling toward the same point: Mechanical assessment is part of the puzzle, not a total solution.

Even so, I think a mechanical assessment that’s not biased towards a certain facet construction to be preferable to one that is biased - even when serving as just a 'piece of the puzzle.' I don't know enough about Imagem to know if it has such bias.

 

[oldminer]

As always, send a diamond of each sort and we''ll examine to see if there is a hidden "bias" in the programming. It is unintentional if it exists. My experience has been that super performing stones get high scores and lesser stones get appropriately lower grades. The kinds of nuance grading differences that make one beautiful stone a little different from another version of a beautiful stone don''t move it out of the top end overall.

It is quite possible that the style of cutting could be diagnosed or distinguished by examination of the separate grading features of Briillance, Sparkle and Intensity.

 

[JohnQuixote]

Date: 8/22/2005 9:05:11 AM
Author: strmrdr

When you say it comes down to 'it will be a matter of human perception and taste' is exackly my point.
Using one machine and one light envirement to test diamonds DOES NOT WORK!

I dont know how to apply the test results from the imagem machine and where they fit into the tool chain therefor it does not go on MY tool chain.
Thats the bottom line.

I agree that one machine-light environ doesn't work. I accept BS as a piece of the puzzle for consumers who seek it, though my questions/criticisms about it are well-documented. Actually, I'm quoted verbatim on the GemEx site’s FAQ, which is gratifying; Someone is paying attention to meaningful discussions here. Over time some of the criticisms have been answered while others may be in-process or dismissed.

Dave's participation and attention here is appreciated. If we have come to consider Brilliancescope as a ‘piece of the puzzle’ it would be irresponsible to dismiss Imagem out of hand. It should be afforded the same opportunities to make a mark. The two technologies may even have something to learn from one another - but that seems unlikely given that they seem to be squaring off. Imagem may remain a separate puzzle piece, telling us something different than BS or Isee. If that’s the case, so be it.

Amidst this 'much ado about blinking lights' we mustn't lose sight of the priorities. There is a grounding fundamental that Bill voiced in the 'other' Imagem thread:

"Diamonds are (as all gemstones) little individual creations of Mother Nature. As I have written before - Mother Nature Fickle finger of Fate (i.e. usually the middle finger with a long sharp fingernail) shows us that just when you think something is totally consistent, it turns out not to be. Another factor in diamond light performance and calculation ray tracing predictions is the type of stone, the size of the stone, length to width ratios, light absorption, sight preferences, inclusions, graining, orientation and much more. Now if some computer whiz can program all the factors in to some future kind of software, then maybe it will be possible, but as of now, basic assumptions, considerations of multiple testing, and very advanced examinations is the best I believe that is available. There is no easy automatic basis of comparison that is totally reliable without experienced human participation along with the tech stuff."

That gets my vote for quote of the month.

I am not opposed to any of these approaches – BS, Isee or Imagem - until someone tries to elevate it to a substitute for ‘experienced human participation.’ Then I call 'BS' (sorry4pun).

These are all tools with reasonable functions, but no amount of machinery or simulation will ever trump experienced human participation and expert perception... And I am not talking about perception of the layman. I am referring to that of experts with a lifetime of actual diamond experience (whether cutting, grading, appraising, science-ing, or just behind the counter) and of working with people from all walks of life to understand beauty and taste. Such experienced human perception can never be matched by software or pixel counting.

 

[strmrdr]

John
"Dave''s participation and attention here is appreciated." I agree 110% with that statement.

Thats one of the things that is so frustrating if it was anyone but Dave or a few others I wouldnt be banging my head against the wall trying to get the information I need to apply it.
Id have just said forget it not worth my time.

 

[JohnQuixote]

Date: 8/22/2005 2:44:47 PM
Author: oldminer

As always, send a diamond of each sort and we'll examine to see if there is a hidden 'bias' in the programming. It is unintentional if it exists. My experience has been that super performing stones get high scores and lesser stones get appropriately lower grades. The kinds of nuance grading differences that make one beautiful stone a little different from another version of a beautiful stone don't move it out of the top end overall.

Thank you Dave.

Brian saw a few candidates evaluated at your presentation, but we will require more evidence and an actual study with controls and test subjects to arrive at concrete assessments.

Garry’s review for the journal included this statement: “Prof A would not describe the lighting environment, but both he a Dave maintain it is a very reasonable environment. They claim however that the light will not favor symmetrical stones the way ISEE2 and BrillianceScope do with their respective rotating bar light and circular ring light.”

Can you elaborate?

Date: 8/22/2005 2:44:47 PM
Author: oldminer

It is quite possible that the style of cutting could be diagnosed or distinguished by examination of the separate grading features of Briillance, Sparkle and Intensity.

I have a myriad of questions about the quality descriptors, some of which may have been addressed (?)

Brilliance as a combination of brightness and fire, I understand. Intensity could be considered a measure of contrast as I read it (correct me if I wrong), but what of sparkle?

GIA has defined scintillation as 'sparkle' and 'pattern.' AGS is moving towards scintillation being defined as dynamic fire (dispersion through a range of motion) + dynamic contrast (contrast patterns through a range of motion). The two approaches meet in the middle with contrast/pattern. AGS dispersion/GIA sparkle is a bit harder to reconcile.

Serg, who is kindly participating here, was quoted at the IDCC in 2004 as saying "We are unaware of current devices that can analyze a diamond through a range of tilting, or use many small (distant) light sources, to correctly estimate scintillation." The point being made is that a diamond's many daily panoramas of illumination are incalculable, so attempting to measure scintillation in one metric from an infinite number seems random. This is one of my biggest criticisms of BS' 'scintillation' metric.

Can you describe how Imagem's 'Sparkle' may differ from conventional use of the term scintillation, or - if it doesn't - clarify the approach?

Forgive me if this has been answered elsewhere. If you can point to the post/thread I'll continue there. There seem to be two ongoing threads.

 

[oldminer]

ImaGem definitions below:

Brilliance represents "average light return." It is measured as the average of gray scale values of pixels within the girdle area. This value can range from 0 to 255 as a property of the measuring device. For the standard lighting level used this value is purposely kept low to prevent saturation. Higher value on Brilliance represents: more brilliant, brighter, excellent cut stone, more efficient stone returning more of the incident light back.

Sparkle represents "variation" in light return. It is measured as a variation in the gray scale values of pixels within the girdle area. Theoretical maximum standard deviation for 40 pixels is about 129. Sparkle represents the degree to which a diamond is lively, dynamic, and responsive to kinetic behavior. Higher the value, more lively, more dynamic a stone is likely to appear to a viewer.


Sparkle is the "Potential" to scintillate. It is a static measurement taken that ImaGem uses to describe scintillation potential.

We will cooperate in grading diamonds sent in as this is something that must be done, We are not going to provide free grading to the world, but we'll work hard to see that the story is told and that information of results is made available.


Garry’s review for the journal included this statement: “Prof A would not describe the lighting environment, but both he a Dave maintain it is a very reasonable environment. They claim however that the light will not favor symmetrical stones the way ISEE2 and BrillianceScope do with their respective rotating bar light and circular ring light.”

The lighting environment inside the system, The Normal Lighting Environment created by ImaGem is considered intellectual property of ImaGem and they do not seem inclined to reveal their lighting model. I have looked inside and know it is not very complex, but I am told that it provides a place where a diamond can be analyzed and the results can be depended upon. My own time with these devices, and the extensive testing that others have done on the devices, have proved that the system works and provides meaningful and consistent data. Symmetrical arrangement of facets does seem to enhance the judgment of beauty in a diamond, just like a symmetric face on a person seems to add to their attractiveness. I think Dr. A was saying that the machine does not have a built in bias to grade symmetry as if it was beautiful alone, but one must recognize the added element symmetry brings to the overall judgment of quality and beauty. The quote above is out of context and I hope this short explanation makes it more clear. It is my thought that the ISEE2 device has a certain symmetry bias that favors the ISEE2 production diamond.....I could be wrong, but that is what I believe is going on. Remember, the ISEE2 is a sales tool and goes hand in hand with the ISEE2 diamonds being sold where the machines are installed. They are very neat machines with a super design, but I am left in doubt of their objectivity. The appearance of bias is built right in as it is a specific sales device. The BS scope has a lighting environment very different than a realistic environment. I have been told that the results of testing diamonds with it are inconclusive. Sure, it identifies great diamonds. Truthfully, we can do a lot of that with our eyes. How accurately it grades diamond performance is what is questionable. What evidence of accuracy is provided anywhere? I think it has been tested in places and rejected as being a cool tool, but not scientific.....I have never tested one myself.

Intensity is measured as a ratio of pixel areas with high levels of light return to the total area within a girdle. In theory this value can be as high as 1000, but under selected lighting condition the value has not exceeded 500 yet. Intensity level represents well defined areas of contrast and pattern and hence gives a stone a "pleasing visual definition", "interest" and "mystique." Stones with high levels of optical symmetry score very high on this scale. But other types of cut may score well on this scale as well.


Intensity has something to do with a diamond's symmetry. It has something to do with a diamond's contrast from its background.

If imagine a fairy spreading sparkly fairy dust as it flys one has scintillation without pattern. Pretty but not eye catching. When one defines a pattern or makes an object that is well visualized against a background, then one has created INTENSITY. A broken mirror's bits will give you scintillation on the floor, but if one took the time to arrange and angle these bits into a tight, carefully shaped, unit with each mirror bit properly angled, then one would have the same potential light return as before, but a far more interesting and eye catching object than just mirror bits at random...... I know the analogy is a little bit of a brain twister, but it does make sense...

Thanks.

 

[strmrdr]

Brilliance = light return – not separating out colored and white light

Sparkle = contrast brilliance = the difference between the blacks and white in a diamond. ISEE2 is similar to this using indirect light then goes on to consider patterns and distribution of the contrast elements the best Iv been able to figure it out.

Intensity is similar to sparkle but the base line is not on the diamond itself but a predetermined background point.

Kewl so far.

See if they will answer this, the exact makeup of the lighting they are not going to share are they willing to share what natural lighting it most closely resembles?
sunlight, florescent, direct, indirect or mixed?

A database of know good performers would with a comparison of results of other tests.

The results of multiple runs on the same diamond by an independant 3rd party on multiple machines.

More 3rd party reviews

Those things would make huge strides towards me being able to accept and use the results it produces.

 

[belle]

Date: 8/23/2005 9:02:30 AM
Author: strmrdr
Brilliance = light return – not separating out colored and white light

Sparkle = contrast brilliance = the difference between the blacks and white in a diamond. ISEE2 is similar to this using indirect light then goes on to consider patterns and distribution of the contrast elements the best Iv been able to figure it out.

Intensity is similar to sparkle but the base line is not on the diamond itself but a predetermined background point.

Kewl so far.

ditto...cool

Date: 8/23/2005 9:02:30 AM
Author: strmrdr
See if they will answer this, the exact makeup of the lighting they are not going to share are they willing to share what natural lighting it most closely resembles?
sunlight, florescent, direct, indirect or mixed?

from what i''ve read, it resembles north daylight at 5500 degree k

Date: 8/23/2005 9:02:30 AM
Author: strmrdr
A database of know good performers would with a comparison of results of other tests.

The results of multiple runs on the same diamond by an independant 3rd party on multiple machines.

More 3rd party reviews

that is what i want to see as well.