2006 GIA grading report - Post info here please

[JohnQuixote]

Date: 1/19/2006 1:34:02 PM
Author: oldminer

No need to fear commoditization of natural diamonds. There are many, many levels of excellent light performance. Not all ''excellent'' are identical. There are rather broad ranges of clarity and color within each grade and they are somewhat subjective as well. While we can hope to define an individual diamond better for consumers, it will not ever reach the commodity stage.

There are good points to this effect here and the other thread you started about branding, Dave. When developing their new performance-based system AGS was sensitive to the commodities concerns and included these examples to demonstrate the broad ranges and different looks within a grade.

AGS4 includes both P410t65c298 and P426t51c324
AGS3 includes both P418t49c338 and P416t68c304
AGS2 includes both P400t55c382 and P412t63c302
AGS1 includes both P412t58c322 and P402t55c372
AGS0 includes both P418t47c338 and P412t61c328

I wonder if GIA could demonstrate (or if someone can calculate) similar ranges/looks for EX, VG and G... Or would that be going against the software limitations clause?

 

[JohnQuixote]

Date: 1/20/2006 9:48:05 AM
Author: strmrdr

Date: 1/20/2006 3:49:41 AM
Author: Serg

Edit. Fine . Can we remember this post like Edit_commodity_Str?

Edit_commodity_Str was good point, but I think it was wrong point. I will try explain my opinion.

Each Brand should have more or less same products inside brand. But different Brands could and should have different products.

All *8 are more or less same but quite different from WF.

All BMW 7 are more or less same, but quite different from Audi 8. There are a lot of other fine car, like Lexus, Acura, Infiniti, Porsche, Ferrari, ..

Beautiful market. what type car parameters do labs test? I know only -'Safety'

To Imagine ASG or GIA performance grade for car market. Could be it good for car market?

Ideal car, Super Ideal car, Excellent car, bla, .. bla Which car is Ideal? For whom this car is ideal?

*8, WF, .. are doing good job. They try do unique product for one type consumer.

AGS and GIA cut performance grade is coin with two sides( One is very good, other is very bad). Labs and Debeers are moving diamond market to commodity market

Well if cars where sold like diamonds you would pay 80% more for a light brown car than a dark brown car and 300% more for a white one.

what cars are graded on in the USA by labs:
The epa rates the fuel economy.
The gov. and insurance companies rank them by size.
The gov. and insurance companies rank them into type: SUV, sports car..
the gov. and several private groups rate safety,, 5 star safety rating and all that jazz.
They are rated for speed to see which tires they can have legaly installed. They have to have tires that are rated for the top speed they can go.
Several groups track and rate long-term reliability.
several groups rate performance and comfort
then of course you have the famous blue book that sets the resale pricing in much the way rap does for diamonds with discounts back from book.

Will there be a group that gathers all that information and awards certs. Could happen if consumers wanted it.

Serg, you have a great sense of humor.

I suggest that cars are a hard comparison, because people grow up riding in/working on/learning about cars each day of their lives. The buying public understands cars. People do not understand diamonds nearly as well. But - I think your lab comparison can work: It is a matter of what the buyer is seeking:

1. What do people seek in a car? Safety & Engineering. Auto labs assess these things.
2. What do people seek in a diamond? Performance & Durability. Diamond labs assess these things.

1. Cars that pass lab tests (all of the brands you named) have different characters. After passing basic tests a consumer can decide which car appeals most to him/her, and spend accordingly.
2. Diamonds that pass lab tests have different characters. After passing basic tests a consumer can decide which diamond appeals most to him/her and spend accordingly.

1. If a car does NOT pass the lab tests for safety & engineering consumers should be made aware of it.
2. If a diamond does NOT pass the lab tests for performance & durability consumers should be made aware of it.

My point is one Bill summarized earlier: Having a system is preferable to not having a system (NOT for us on PS, but for the buying public). Just like labs protect consumers from buying exploding cars, the AGS (and GIA too) protects consumers from buying 66% depth, ultra shallow or otherwise nasty diamonds by FAILING them in their tests.

I understand we will debate the top of the metric, but having SOME criteria at the bottom to protect consumers is a good thing.


>

It's not 'official,' Strm, but do you subscribe to Consumer Reports? I do. I use it for rejection… Kind of like a HCA for my toaster.

 

[Garry H (Cut Nut)]

Date: 1/20/2006 9:48:05 AM
Author: strmrdr

Date: 1/20/2006 3:49:41 AM
Author: Serg

Date: 1/19/2006 2:36:09 PM

Author: strmrdr

Edit

Edit. Fine . Can we remember this post like Edit_commodity_Str?

Edit_commodity_Str was good point, but I think it was wrong point. I will try explain my opinion.

Each Brand should have more or less same products inside brand. But different Brands could and should have different products.

All *8 are more or less same but quite different from WF.

All BMW 7 are more or less same, but quite different from Audi 8. There are a lot of other fine car, like Lexus, Acura, Infiniti, Porsche, Ferrari, ..

Beautiful market. what type car parameters do labs test? I know only -''Safety''

To Imagine ASG or GIA performance grade for car market. Could be it good for car market?

Ideal car, Super Ideal car, Excellent car, bla, .. bla Which car is Ideal? For whom this car is ideal?

*8, WF, .. are doing good job. They try do unique product for one type consumer.

AGS and GIA cut performance grade is coin with two sides( One is very good, other is very bad). Labs and Debeers are moving diamond market to commodity market

Well if cars where sold like diamonds you would pay 80% more for a light brown car than a dark brown car and 300% more for a white one.

what cars are graded on in the USA by labs:
The epa rates the fuel economy.
The gov. and insurance companies rank them by size.
The gov. and insurance companies rank them into type: SUV, sports car..
the gov. and several private groups rate safety,, 5 star safety rating and all that jazz.
They are rated for speed to see which tires they can have legaly installed. They have to have tires that are rated for the top speed they can go.
Several groups track and rate long-term reliability.
several groups rate performance and comfort
then of course you have the famous blue book that sets the resale pricing in much the way rap does for diamonds with discounts back from book.

Will there be a group that gathers all that information and awards certs. Could happen if consumers wanted it.

I think you can see from you good list Storm that what the government does is . what type car parameters do labs test? Sergey quote: I know only -''Safety''

BMW 7 are more or less same, but quite different from Audi 8. There are a lot of other fine car, like Lexus, Acura, Infiniti, Porsche, Ferrari, ..

The parts of your comments that help us make this distinction between which car and which model will we buy - this is not the role of labs as they stand.
Pricescopeand HCA is for example one of those rating bodies (although HCA is not good enough for the job alone).

What Sergey is getting to is the need for a useful beuaty grading system like the www.erobertparker.com Robert Parker guide and www.wired-vig.wired.com/wired/archive/9.11/wine.html?pg=1&topic=&topic_set= some sort of analysis method.

An analogous wine story: A biochemistry company called Enologix, run by Leo McCloskey , claims to be able to predict the quality of wine, and aid the making of better wine. McCloskey has identified several hundred distinct chemical compounds that make up fermented grape juice - tannins, phenols, anthocyanins, essential oils, etc that are responsible for the ‘Basic Responses’ of flavors, smells, and colors that, in different proportions, make one wine cost $100 and another $10. He did this by analysing wines with gradings from a famous US wine critic Robert Parker who rates ‘basic taste responses’ like acidity, fruit, sweetness, tannin, flavor, color etc. and gives an overall score out of 100 for each wine. Along with a score, there are ‘tasting notes’ of basic wine characteristics that guide wine lovers in selecting for personal preferences. One consumer may prefer sweet but crisp acidic wines, while others prefer bold tannin based wine with strong fruit flavors; but both could score say 90 on a scale where 100 is the best possible.

 

[JohnQuixote]

I prefer bold tannin based wines with fruity overtones (blackberry especially) - and Porsche.
Top down. Wind going through my...err...hair?

Thank goodness for cars and wines or we might have nothing to chatter about here.

 

[Serg]

re:Well if cars where sold like diamonds you would pay 80% more for a light brown car than a dark brown car and 300% more for a white one.

Yes, if color natural and rare.

Is blue fancy diamond more beautiful than yellow fancy diamond? I think no.

Client pay ( in luxury product) for exclusive( not only of course, but price can no be high without exclusive).

If you have car paint:
1) New
2) Deep ( Good Saturation) Without big flash on Sun.
3) High tech. Can change Brightness and Tone depends from viewer condition. For example black on sun and white in Moon.
4) emphatic and sexy
5) Do not create by Human. It is from meteorite. You have portion for 9 cars only.

You can take any 9 luxury cars, repaint and sell with additional cost èèèèèèèè$ for each car.

If such paint can be produce in any volume You can add èèè-èèèè$ to bill only.

 

[Serg]

I suggest that cars are a hard comparison, because people grow up riding in/working on/learning about cars each day of their lives. The buying public understands cars. People do not understand diamonds nearly as well.

Who is guiltyin such status ?

Are anybody can explain me:
1) What are rules for symmetry grade? What is symmetry grade at all./
2) What is girdle thickness?
3) What is difference in clarity grades for bug and small diamonds?
4) What is GIA and AGS cut grade rules? What is connection between labs grades and real beauty?
5) Color. DO not speak about color at all, It is too difficult.
Yes , simple People can not understand diamonds(labs rules). "Simple people" mind is not enough to solve such hard task. Only High level pagans has enough clandestine knowledge for understanding diamond. We all should follow only,/

 

[adamasgem]

Date: 1/21/2006 7:44:54 AM
Author: Serg

I suggest that cars are a hard comparison, because people grow up riding in/working on/learning about cars each day of their lives. The buying public understands cars. People do not understand diamonds nearly as well.

Who is guiltyin such status ?

Are anybody can explain me:
1) What are rules for symmetry grade? What is symmetry grade at all./

Sergey: Since the file size is too large for PS posting, I've sent you an extract from the GIA internal lab manual on symmetry, under fair use for education, regarding how they did grade symmetry..

WHO knows how much they have relaxed this in the past few years..

Unfortunately GIA does not quantify the level of symmetry faults, other than qualitatively categorize them subjectively
as to "minute", minor,noticeable,obvious or prominant.. SO there is a lot of wiggle room. Additionally ther "paper" does not alwas show EXTRA FACETS, whch of course effect symmetry automatically, as they have(had) an nternal category called "non callable" extra facets, those where a grader can't see them in the absolute face up position, and are often used to help out a clarity grade..

 

[JohnQuixote]

Date: 1/21/2006 7:44:54 AM
Author: Serg

(JQ): "I suggest that cars are a hard comparison, because people grow up riding in/working on/learning about cars each day of their lives. The buying public understands cars. People do not understand diamonds nearly as well."

Who is guiltyin such status ?

Are anybody can explain me:

1) What are rules for symmetry grade? What is symmetry grade at all./
2) What is girdle thickness?
3) What is difference in clarity grades for bug and small diamonds?
4) What is GIA and AGS cut grade rules? What is connection between labs grades and real beauty?
5) Color. DO not speak about color at all, It is too difficult.

Yes , simple People can not understand diamonds(labs rules). 'Simple people' mind is not enough to solve such hard task. Only High level pagans has enough clandestine knowledge for understanding diamond. We all should follow only,/

Who is guilty? Years of hidden information. And misinformation. The internet has changed that, but you can still walk into stores and be told that polish & basic symmetry = cut. This is deceptive. More info on cut, and a consumer-friendly cut grade helps stop that kind of irresponsible deception.

I don't think GIA and AGS (or Garry/MSU) are pagans. I believe labs demonstrating consistent standards are good for consumers. Without the labs maybe we would go back to selling diamonds as 'canary yellow,' or 'white' or 'blue-white' in color. We could revisit the 1920s and use 1, 2, 3 or I, II, III or A, B, C. One sellers 'A' might be another seller's 'AA,' and another's 'AAA'. Would that be better?

I agree with you on points of optical symmetry grade, girdle thickness, clarity (big and small and eye-clean or NOT eye-clean) and face-up versus side graded color. No one is saying those things can't be addressed. It's a free market and institutions can be influenced. It seems to me that Garry's 'crusade' on the internet (popularizing HCA and ideal-scope) has influenced both of the major labs.

 

[adamasgem]

Date: 1/21/2006 7:44:54 AM
Author: Serg

Are anybody can explain me:
3) What is difference in clarity grades for bug and small diamonds?

Complex question, although there appears to be differences in "standards" depending on size and location. They have, over the years, changed their teachings (i.e. lossened up) what they say about this, and most can talk to what they have seen in "paper".

I don''t say that I disagree with GIA on some of this, larger stones havng the same size inclusion as a smaller one, I don''t thnk should be penalized as much, I think (believe) it is somewhat of a relative thing. Years ago, OKUDA had a microscope with a reticle, such that inclusions could be measured and clarity "grade" set depending on inclusion size. This was the only dfinative thing I have ever seen relative to clarity grading.

 

[adamasgem]

Date: 1/21/2006 4:06:42 PM
Author: JohnQuixote

I don''t think GIA and AGS (or Garry/MSU) are pagans. I believe labs demonstrating consistent standards are good for consumers.

John.. "consistent" and GIA have been proven to be two mutually exclusive words over the years. They seem to be always changing their "minds" ("standards") to loosen things up.. I''ve shown that with the fluorescence issue, and since I''ve got historical "teachings" spanning 50 years or so, can also show that....

That is what "pi**es" me off about an educational institution going down the tubes, but I can''t say that it is exclusive to GIA, just look at high schools, teaching to the lowest common denominator, just to be politically correct.

 

[JohnQuixote]

Date: 1/21/2006 4:22:40 PM
Author: adamasgem

Date: 1/21/2006 4:06:42 PM
Author: JohnQuixote

I don't think GIA and AGS (or Garry/MSU) are pagans. I believe labs demonstrating consistent standards are good for consumers.

John.. 'consistent' and GIA have been proven to be two mutually exclusive words over the years.

Actually, I had the words in separate sentences, mister chain-yanker.

Date: 1/21/2006 4:13:04 PM
Author: adamasgem

I don't say that I disagree with GIA on some of this,

...Wow. I wanted to save that sentence for posterity! (yanking back).

 

[He Scores]

Hi everyone. It''s been a long time since I''ve been on the system. Best regards to everyone, particularly those I visited with in Vegas last summer.

RE: Dave says: A diamond with great light performance, but cut in a way that hurts its durability, finish or spread relationship is rightly judged as not the best. The same follows that a diamond with all satisfactory parameters which does not perform with light as it could if cut otherwise, also is not to be judged a "Best" cut, either.

~~~~~~~~~~~~~~~~~~~~~~

Regarding durability. Since most of the premium stones today don''t have a culet, does this mean they shouldn''t get the top cut grade? After all, the "no culet or v. small culet" is just a prone to chipiping as a thin girdle or the corner on a princess.

Also. These sharp edges may or may not be a detriment depending on the use of the stone. For example, A thin girdle mounted in a bezel setting. A princess with prongs on the sides rather than corners for a pendant.

I think durablility is a saleability issue and shouldn''t be lumped with workmanship.


I also have another issue to raise with regard to the measuring of stars and halves. To measure directly down the rib line of the main facet, through the ribline separating a pair of halves has no relevance to us cutters, mainly because the PROPORTION of these segments will change in the face up view depending on how much the halves are "dug". I explained this to both AGS and GIA at the show, but of course it went ignored.

Good to see all you again....


Bill

Remember, if you don''t know diamonds, it pays to know the score.
BrayScore.coml

 

[Capitol Bill]

It''s always enlightening to hear things from Bill Bray''s perspective. I look forward to seeing you in LV again this year, Bill.
Kind regards,
Bill Scherlag

 

[adamasgem]

Date: 1/21/2006 4:52:11 PM
Author: He Scores

Regarding durability. Since most of the premium stones today don''t have a culet, does this mean they shouldn''t get the top cut grade? After all, the ''no culet or v. small culet'' is just a prone to chipiping as a thin girdle or the corner on a princess.


Bill

Remember, if you don''t know diamonds, it pays to know the score.
BrayScore.coml

Bill:

When a stone is mounted, the culet is protected, the girdle has a bigger chance of not being protected..

Culets usually get chipped or abraded in a parcel, unless some idiot picks them up wrong on tweezers..

Corners on princess cuts are a setter''s nightmare, I am told; a disaster waiting to happen.

I''ve seen princess cut stones that have been apparently been damaged by being picked up with tweezers wrong. (I use silicon covered tips on tweezers as a cushion)

 

[He Scores]

Marty...you''ve made my point. Since durability is only an issue at certain times, why penalize the cutter with giving all stones a poorer cut evaluation? Durability has everything to do with saleability and is basically preference by the purchaser....just like crown height, table percentage, patterning, and...well, you name it. A characteristic of a diamond prefered by one seller over another. It should not be a standard of any sort.

My scoring system takes into account v. thin girdles by applying point deductions in those instances that it occurs, and thereby lowers the score. If it''s the only "mistake" left by the cutter, it wouldn''t turn a top cut into a good cut (if a rubric style system were layed over my scoring system). Then it''s up to the purchaser if he/she finds that an objection to purchasing the diamond.

Also, I''m surprised how many people choose to go on the slippery slope of "good performance = good cut".

Good performance means just that....good look. Performance in a diamond has about five other factors involved other than the cutter''s workmanship. Workmanship should be evaluated by itself IMHO.


Bill

p.s. Thank you Bill S.

 

[strmrdr]

Date: 1/22/2006 8:27:34 AM
Author: He Scores

Good performance means just that....good look. Performance in a diamond has about five other factors involved other than the cutter''s workmanship. Workmanship should be evaluated by itself IMHO.



Bill


p.s. Thank you Bill S.

Welcome back It is good to get the unigue persepective you offer in these conversations.
What are the 5 things?

 

[He Scores]

Thank you Storm....

The five things that affect performance other than cut.

color...there is no performance in a black diamond or opaque colored diamond yet each could have a very fine cut.

clarity. This is obvious. Pattern seeking cutters could have a problem with large or numerous flaws. By measuring "performance" as cut, you''re making an eliteist(sp) system for only better clarity grade stones. clarity affects performance, not cut.

material. some material is just...well....clearer than others, even though the clarity grade will be the same. I''m one of those "dinosaur" cutters Sergei talks about I guess, but older cutters than I would call it..."good or bad water". It''s easily seen if you go through a parcel of stones. Also knaated material can''t be polished as well regular material. Also, some material is "softer" than others resulting in a higher adamatine lustre of each facet....something that''s very important in how a stone shows.

granular structure that the stone is cut on. .... Depending on facet direction during cutting, you can get a good performing stone inspite of other "saleability" objections like finish (cutting lines) or proportion.

cleanliness ..... a clean poorer cut stone (not the poorest vs the best cut) can look much better than a well made stone with surface dirt/oil on it.

lighting conditions... the photograhpers on here have pretty much covered this. An extremely well cut stone is extremely well cut even if it''s in a dark bank vault and isn''t being viewed.


Then there''s my biggest objection of diamonds only being viewed in the face up position, photographed in that position and evaluated in that position. Diamonds are a piece of sculpture, and as such are to be viewed in a variety of lighting conditions and perspectives, just like other sculptures. I believe that this is the one main reason that the "h & a" patterning isn''t fullyl accepted by the trade as being a premium stone, because lots of other people look at stones differently. GIA forced people to look at stones in the face up view with naked eyes in their observation tests. A pre-determination in itself that had it''s flaws. I only had about 50 people take part in my observation tests and did not direct them how to look at the stone. In a vast majority of the cases, when people in the trade were instructed only to evaluate the cut of the diamond, they looked at it with a loupe and tweezers...certainly not the way to see fire or brilliance.

My point is...a "look grade" is ok and has a niche in evaluation. A look grade is a look grade. A look grade is not a cut grade.


Bill

 

[He Scores]

RE: Acceptance by the trade.

Did anyone ever consider the similarity between the "h&a" patterning and bowties in fancies?

Think about it.

Bill

 

[He Scores]

Re: similarity between patterning in stones

 

[He Scores]

RE: similarities in "performing" stones.


What''s celebrated in one, is berated in another.

Your comments are invited.


Bill

 

[belle]

hey bill, thanks for your input. the bowtie correlation is interesting and i have some views i would like to share on it. rather than having the subject get lost in garry''s thread here, i think it would be great if you started a new thread dedicated to the subject.

 

[strmrdr]

Date: 1/22/2006 9:06:27 AM
Author: He Scores

My point is...a ''look grade'' is ok and has a niche in evaluation. A look grade is a look grade. A look grade is not a cut grade.



Bill

interesting and I agree.
Something that bugs me about the whole h&a thing is diamonds that have picture perfect hearts and arrows and look awesome under a scope but the facet angles are all over the place.
To me that isn''t well cut.
A tight diamond speaks to me which is why I love helium reports I get to see how tight a diamond is much better than with a sarin report.
I may not ever be able to see the difference but I know its there.
Sort of like IF clarity is too some people tight cutting is to me.

 

[He Scores]

RE: Something that bugs me about the whole h&a thing is diamonds that have picture perfect hearts and arrows and look awesome under a scope but the facet angles are all over the place.
To me that isn''t well cut.
A tight diamond speaks to me which is why I love helium reports I get to see how tight a diamond is much better than with a sarin report.
I may not ever be able to see the difference but I know its there.


Storm....is it ok to call you that? I''m not on here enough to know everyone''s name.

I''m in the process of evaluating the different machines to measure stones. I am aware that the helium machine claims more ''accuracy'' in the linear measurements but what else do you see that shows how tight a diamond is?

As a matter of fact, my BrayScore analysis may take these things you see, if you''re looking at measurement data, and basically sumarizes them into a single score. My goal is to be able to run reports from ALL machines through the BrayScore analysis platform and thereby creating a tool to measure the performability of the machines.

Ostensibly, what machine was used to generate the data used in scoring would have weight behind it, just like certain labs have more weight than others.

You are certainly correct in saying that patterning stones can be "all over the board" with angle measurements. Since they are cut to make the pattern, other "views" (remember the sculpture analogy) can be distorted. These may or may not include views of an irregular girdle, lopsided facets and lack of definition between facets.

Bill

 

[He Scores]

Belle....I''d love to start another thread and I''d love to sit by my laptop and go into deep discussion on it, but alas, I have stones to cut, and I''m behind.

Be my guest to take those pic and throw them up...I would love to hear what you and others have to say. I''m sure come Monday, the proponents of performance grading will see things differently.


Bill

bill

 

[adamasgem]

Date: 1/21/2006 4:45:24 PM
Author: JohnQuixote

Date: 1/21/2006 4:13:04 PM
Author: adamasgem

I don''t say that I disagree with GIA on some of this,

...Wow. I wanted to save that sentence for posterity! (yanking back).

Actually , I have said t more than once. GIA had it RIGHT when they approached the problem with their WLR metric, trying to take into account the fact that people look at diamonds from all aspect angles. While I dsagreed, and showed that the lighting scenario was not appropriate, I was surprised and disappointed, to say the least, that they backtracked to a face up only viewpoint.

 

[He Scores]

Date: 1/22/2006 11:46:00 AM
Author: adamasgem

Date: 1/21/2006 4:45:24 PM
Author: JohnQuixote

Date: 1/21/2006 4:13:04 PM
Author: adamasgem

I don''t say that I disagree with GIA on some of this,

...Wow. I wanted to save that sentence for posterity! (yanking back).

Actually , I have said t more than once. GIA had it RIGHT when they approached the problem with their WLR metric, trying to take into account the fact that people look at diamonds from all aspect angles. While I dsagreed, and showed that the lighting scenario was not appropriate, I was surprised and disappointed, to say the least, that they backtracked to a face up only viewpoint.

Marty...not to mention in the WLR study they used averages of angles....this is out of the realm of normalcy too. Some of the results showed high return on stones that were borderline "fisheye".

The argument from this becomes..."there are other sets of parameters that make for a brilliant stone", while in reality a fisheye is rejected by the industry from being a premium cut stone.



Bill

 

[adamasgem]

Date: 1/22/2006 11:55:58 AM
Author: He Scores

Date: 1/22/2006 11:46:00 AM
Author: adamasgem

Date: 1/21/2006 4:45:24 PM
Author: JohnQuixote

Date: 1/21/2006 4:13:04 PM
Author: adamasgem

I don''t say that I disagree with GIA on some of this,

...Wow. I wanted to save that sentence for posterity! (yanking back).

Actually , I have said t more than once. GIA had it RIGHT when they approached the problem with their WLR metric, trying to take into account the fact that people look at diamonds from all aspect angles. While I dsagreed, and showed that the lighting scenario was not appropriate, I was surprised and disappointed, to say the least, that they backtracked to a face up only viewpoint.

Marty...not to mention in the WLR study they used averages of angles....this is out of the realm of normalcy too. Some of the results showed high return on stones that were borderline ''fisheye''.

The argument from this becomes...''there are other sets of parameters that make for a brilliant stone'', while in reality a fisheye is rejected by the industry from being a premium cut stone.



Bill

Bill.. Of course the theoretical GIA study was relagated to "symmetrical" stones, by virtue of, in effect, using the "averages" of the angles, which is "incorrect" when you are looking at a particular stone.

As Brayscope or raytracing does, both based on non averaged, but errored, measurements, is to try to quantify the true but different assymetrical aspects of the problem.

Direct measurements have their own "errors" and are much more limited in their ability to reproduce lighting situations such that their measurements of light performance are "meaningfull".

A combination of the two approaches is probably what is needed..

But as you imply, basing a decision on AVERAGES might be taking us back to the stone age, it might get us in the ballpark, but it also might lead us into the garbage bin.

That is why the "symmetry" aspect needs to be codified more than the subjective way it is currently. Bill has tried to do this in Brayscore, as does raytracing based on "actual" measurements.

For those of you who want to understand what Bill s discussing relative to the cutters art and Brayscore, look at published US patent application 20040051861 on the USPTO web site http://www.uspto.gov . It is an interesting read, and goes into a good deal of detail on what he is trying to do. I can''t say I agree on all in the patent, and I''ve had long and interesting discussions about it with him.

 

[strmrdr]

Date: 1/22/2006 10:52:02 AM
Author: He Scores



Storm....is it ok to call you that? I''m not on here enough to know everyone''s name.


I''m in the process of evaluating the different machines to measure stones. I am aware that the helium machine claims more ''accuracy'' in the linear measurements but what else do you see that shows how tight a diamond is?


Bill

storm is fine :}
Im aware of your bray score system and think it has a lot of potential I like the idea behind it.

sarin ogi vs helium
the biggest thing I notice is consistency of helium measurements.
This is for rounds measurements in degrees:
AGS uses helium for the numbers on its reports up to 8mm
GOG''s helium numbers match up with the rounded to .1 AGS numbers always.
GOG''s sarin numbers almost always match within the sarin rounding errors except on painted girdles. they measure to .02 then round to .1 and then average so that can make a small difference compared to AGS/helium .01 then average then round from the AGS certs.
The actually helium report has the measurements out to .01 and i believe actually measures out to .001 range.
But another popular vendors sarin numbers arent close to the AGS helium numbers most of the time.
Both are using the top end sarin machine.
the ogi numbers iv seen reported are far enough off the AGS numbers that I consider it useless.

If you take the helium data and the sarin data and import it into diamcalc and compare the virtual models generated to the real thing the models are much more accurate for the helium data.
Especially on diamonds with painted girdles.
The gog sarin data is set to max accuracy setting where the helium is set to the default 400 pictures with 800 pictures available in a very very slow mode.
The differences between the 400 and 800 mode are small and on most rounds not enough to change any number more than .01 if that.

When it comes to asschers the helium scan is the only acceptable to me data for 3d modeling.
The sarin cant track the facets well enough to generate accurate data and often inserts extra facets in an attempt to make the measurements work which don''t exist on the real diamond.

All of this of course is my opinion and some may disagree. :}

 

[He Scores]

Storm my man...thank you for the lesson on measuring machinery. I guess I''ll have to call Serg and see about getting a helium machoine.

Just got off the phone with Marty and he''s pretty much told me the same thing..

Now I''m WAY behind in my cutting.


Bill

 

[adamasgem]

I guess GIA, in their latest "ad" in their alumni publication The Loupe, took note ot President Clinton's hyperbole, to paraphrase "It all depends on what the meaning of the word is, is".

I guess that is what they looked to to justify the words "actual proportions"... given ther penchant to redefine rounding to their convenience..

Might get them into trouble...