Consumer advisory: GIA Cut Grade Rounding Problems

[He Scores]

I can live with your statement about differences, but the devices like Sarin/Ogi are full of machine error, averaging, rounding, etc. Nothing is more accurate than a direct measure. A calculation based on corrupted data is pretty much a corrupted final product.

I agree. But we have to establish an acceptable standard of error with regard to measuring. I find it interesting that machine owners talk about error in their measuring but when they use their measurements they make averaging measurements a "norm" which gives a more false analysis than the "corrupted" data. Also, they use incorrect measurements or measurements that have no meaning to the cutter.

My scoring anaylysis(for the time being) uses the Sarin data and I''ve found that only about 50% of trade eyes can detect a 6% deviation in final scores.

It can be made to accept any measuring machine''s data, so in effect the BrayScore platform can be used as some sort of replication/accuracy tool to judge various measuring devices for accuracy and replication.

However, like clarity grading is acceptable by 10X, I think cut measurements are at an acceptable standard where they''re at now, IMHO. Just because technology allows us to measure more accurately, doesn''t mean that it''s necessary or is beneficial to do it.

I''ve heard of machines being able to measure the polish on facets in "nano angstroms" or something like that. Totally ludicrous. Can it be done? Sure. Will it help us sell more diamonds? I highly doubt it.


Bill Bray
Diamond cutter

 

[adamasgem]

Date: 2/20/2006 12:45:36 PM
Author: He Scores


3. Durablility. I''ve stated this before in this forum. Two things about durablility. It''s a saleability factor more than a pricing factor. Why? Sharp edges/points are more and less significant depending upon the utilization of the diamond. Also, durability can''t be cherry picked i.e. take off for knife edge on one spot of a round brilliant''s girdle and not for a corner on a princess cut or a ''no culet'' on a premium cut stone.



Bill Bray
Diamond Cutter

Bill:

There is a big difference to the consumer between a pointed culet, which does not effect durability from a consumers standpoint, but does when in a dealers parcel, and knife edges, which are extreme consumer and setter''s durability factors when in a ring (as well as in a parcel), and only give setters nightmares when they are in earring or pendants, not being strong consumers issues when they are not subject to the wear and tear of a ring.

I disagree with you that it is not a pricing issue, as if I were a jeweler, I would want to buy loose diamonds where I wouldn''t have to worry about whether they were appropriate for only earrings or not. That dual use concept effects pricing, like it or not..

 

[adamasgem]

Date: 2/20/2006 1:50:05 PM
Author: oldminer
1. Physical cutting parameters are much more accurate in designating differences between stones than performance observations as long as the proper measurements are being taken, not averaged or unduly penalized.

I can live with your statement about differences, but the devices like Sarin/Ogi are full of machine error, averaging, rounding, etc. Nothing is more accurate than a direct measure. A calculation based on corrupted data is pretty much a corrupted final product.

Dave: But those measurements are needed to extrapolate to consumer lighting conditions you (as well as others) can't and don't "measure", let alone DEFINE, for peer review.

What are appaisers going to say to their clients, we have this piece of paper that the "generator" says is the be all, end all, yet they won't tell us what it is based on. Would you as an "expert", get on a witness stand and say that the opinion on the paper is correct, given the information released.

I hope your answer to that question would be the same as I would give, a resounding NO!, BECAUSE I, and others, have ZERO information to base an opinion on, other than marketing mumbo jumbo, similar to the oft quoted "trust me, it is a G" that we hear about pertaining to less than scrupulous jewelers and mass marketers who call themselves jewelers.

We in the industry, know "paper" we can (sometimes) trust, and we also know about "paper" which would have a better use if it wasn't laminated, so that it would be softer when you wiped your rear end with it

.

Use your influence to promote openness.
Only then, can "informed" people make rational and accurate decisions on the validity of claims.

Those that can't understand the concepts or results, rely on some of us to give an informed opinion after debating the issues involved.

 

[strmrdr]

Date: 2/20/2006 2:27:53 PM
Author: He Scores

I've heard of machines being able to measure the polish on facets in 'nano angstroms' or something like that. Totally ludicrous. Can it be done? Sure. Will it help us sell more diamonds? I highly doubt it.

depends on who is buying.
Id be interested in that info!! :}

The problem is that the vendors who arent willing to invest in the better machines are holding things back.
They would rather whine than spend the money to get with the times.
Which gives gia an excuse for using rounding which brings us right back to the start of this 11 page thread :}

 

[RockDoc]

Date: 2/20/2006 5:00:44 PM
Author: strmrdr

Date: 2/20/2006 2:27:53 PM
Author: He Scores

I''ve heard of machines being able to measure the polish on facets in ''nano angstroms'' or something like that. Totally ludicrous. Can it be done? Sure. Will it help us sell more diamonds? I highly doubt it.

depends on who is buying.
Id be interested in that info!! :}

The problem is that the vendors who arent willing to invest in the better machines are holding things back.
They would rather whine than spend the money to get with the times.
Which gives gia an excuse for using rounding which brings us right back to the start of this 11 page thread :}

Why wouldn''t vendors buy this equipment?

One has to ask as a business person, how would they get a return on the investment? Let''s say for "fun" a seller or appraiser does make an investment in a piece of technology. Given most of the equipment has a useful life span (probably 2-5 years until something better is produced or you have to buy the software upgrades or have the machine serviced) has to be factored into just how many purchasers would want that information in order to make a purchase or have an appraisal done?

Let''s say this equipment is medium priced at $ 10 - $ 15 K. Your cost at the high end is $ 3000.00 per year, plus the labor time of the person to perform the test. Just to break even on the investment at $ 10.00 extra per stone, you''d have to make make sales you wouldn''t have made for 300 stones per year to even consider making that purchase.

How many consumers wouldn''t buy a diamond without having that info. Let''s take you for example.... How many diamonds did you buy over the past year or so and what were the dollar amounts paid? Even on this forum of 3500 participants from time to time, how many others besides yourself would deem this a necessity for the purchase of a diamond?

This is why such equipment isn''t purchased. From the major lab postion, yes they could factor the cost over thousands of stones per year, but if they graded a stone that didn''t have the ultimate polish grade, how many times would the stone have to be resubmitted, to get, and even further how many diamond cutters would want to add this potentially incredible "time suck" to the production cost?

Remember plenty of sellers do have Sarins/ colorimeters, microscope, sas 2000''s, B Scopes and more, that only a small percentage of the diamonds actually cut and sold are even proportioned to the "best" standards.

Maybe you should buy one of these and offer the service?

Rockdoc

 

[belle]

thanks for putting that back in perspective rockdoc

 

[strmrdr]

nice job of totally missing the point RockDoc lol

but to address your point:
There are a lot of people that want a high level of information that keeps you and a few vendors in business.
There must be a demand for it or why would you buy a b-scope,gog a helium scanner, Richard a sas2000 and all the other toys.
Kinda defeats your whole point.

 

[RockDoc]

Date: 2/20/2006 5:58:14 PM
Author: strmrdr
nice job of totally missing the point RockDoc lol

but to address your point:
There are a lot of people that want a high level of information that keeps you and a few vendors in business.
There must be a demand for it or why would you buy a b-scope,gog a helium scanner, Richard a sas2000 and all the other toys.
Kinda defeats your whole point.

NO, Ihaven''t missed the point at all.

I was addressing just how many people would want to split hairs so much that ths surface of facets is now analyzed, from a purchasing perspective.

But you still didn''t answer my questions as to how many diamonds you''ve bought, how much you spend with vendors. Maybe if you bought a significant amount of stones - they would consider providing the information you seem so interested in.

In my view the number, of people seeking this is almost non existent, as compared to those "requiring" such information to make a purchase.

If you feel it is so needed, why don''t you do as I suggested... buy the equipment and offer the service???

I''m not saying this to be offensive. I am making the suggestion, that if you REALLY think it is there is that much of a market for this information, put YOUR money where your mouth is. Take the risk, maybe it will be something you can make money from to further feed the diamond insania?

Rockdoc

 

[belle]

Date: 2/20/2006 5:58:14 PM
Author: strmrdr
nice job of totally missing the point RockDoc lol

but to address your point:
There are a lot of people that want a high level of information that keeps you and a few vendors in business.
There must be a demand for it or why would you buy a b-scope,gog a helium scanner, Richard a sas2000 and all the other toys.
Kinda defeats your whole point.

two of your three are appraisers strm…that's completely different. they don’t buy the diamonds they analyze. that is their market. consumers wanting a full appraisal expect that level of information from them. i guarantee not everyone needs it. bill and rich are rare exceptions anyway, since many appraisers don’t even have sarin.
you need to remember the internet is less than 10% of sales…even blue nile doesn’t invest in helium or bscope or sas…just gcal…and they are the largest! this means over 90% of sales are live and most people are content with knowing they have a report from a major grading lab just guaranteeing they have in fact a real diamond.

if you hit the lottery maybe you can create the kind of demand you want.... but it would have to be a big lottery.

 

[He Scores]

RE: and even further how many diamond cutters would want to add this potentially incredible "time suck" to the production cost?


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


Actually, this "time suck" is an angle that I was concerned about, since no one''s really willing to pay us cutters to do nicer and nicer work.

Plus what I said earlier.


Bill Bray
Diamond cutter

 

[strmrdr]

and you still miss the point....
GIA has said they used the rounding because its all the accuracy the cheapest machines can produce.

...........
Locally in my area:
one jeweler has added a b-scope and the high end sarin
A couple others have added sarin machines
Another is looking at the isee2 machine
Im not the only one wanting more info.
Its not just a few online crazy people wanting more information its a consumer revolution in the making.
Those that get it will survive those that don''t wont.
........

now as too how many have I bought .. it is really none of your business. iv mostly been buying colored stones but if you count all sizes of diamonds the number is around 25 but iv had a say in hundreds if not thousands of sales online :}
isn''t the net awesome! :}
We the people of PS have power well beyond what is in our pocket books at any given time.
I don''t need to win the lottery and buy a thousand diamonds to move mountains.
I didn''t become the industries most hated consumer thru the power of my pocketbook :}
Mostly did it by asking questions and being bullheaded enough to get the answers :}

 

[strmrdr]

Date: 2/20/2006 7:42:17 PM
Author: He Scores
RE: and even further how many diamond cutters would want to add this potentially incredible ''time suck'' to the production cost?




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



Actually, this ''time suck'' is an angle that I was concerned about, since no one''s really willing to pay us cutters to do nicer and nicer work.


Plus what I said earlier.



Bill Bray

Diamond cutter

There is a small but growing number of consumers who are.
So take heart :}
The center of the revolution is here at PS.
GOG, WF, the infinity network, prove every day that people are willing to pay extra for the skilled cutters producing the best diamonds possible today.

That is my biggest problem with the new GIA system I see it as a step backward.
The AGS system while not perfect is a step forward by rewarding better cutting.

 

[RockDoc]

Date: 2/20/2006 7:45:09 PM
Author: strmrdr
and you still miss the point....
GIA has said they used the rounding because its all the accuracy the cheapest machines can produce.

...........
Locally in my area:
one jeweler has added a b-scope and the high end sarin
A couple others have added sarin machines
Another is looking at the isee2 machine
Im not the only one wanting more info.
Its not just a few online crazy people wanting more information its a consumer revolution in the making.
Those that get it will survive those that don''t wont.
........

now as too how many have I bought .. it is really none of your business. iv mostly been buying colored stones but if you count all sizes of diamonds the number is around 25 but iv had a say in hundreds if not thousands of sales online :}
isn''t the net awesome! :}
We the people of PS have power well beyond what is in our pocket books at any given time.
I don''t need to win the lottery and buy a thousand diamonds to move mountains.
I didn''t become the industries most hated consumer thru the power of my pocketbook :}
Mostly did it by asking questions and being bullheaded enough to get the answers :}

No, Storm, you miss the point.

For the instrumentation that we feel there is a demand for, many appraisers as well as sellers have made the investment in purchasing the equipment and taking the risk of ROI.

I am speaking specifically of the information that you specified getting... a machine that would grade polish in nano angstoms.

I may be wrong but I don''t believe such a piece of equipment actually exists. The measurement of nano angstoms is such a tiny measurement, that I believe it is impossible for such a machine to exist. There is a piece of equipment that will analyze the flatness of a facet. You''re talking about a service that as a consumer, you appear to be the only interested party of getting that info.

There is consumer demand to know what Sarin machines, SAS''s, Helium machines, B Scope machines etc. do and as such those who attempt to offer complete evaluation services have made the investment. WHY ? Cause there is a recongizable demand for the information. This is CURRENTLY NOT the case with nano angstrom meausurement results of the quality of polish of a facet on a diamond.

But that aside, you''ve bought 25 stones? Most of them were colored stones as well. Interesting.... but you hardly qualify as a true gem junkie.

So... how many of those were diamonds, where you had them tested by B Scope, Sarin and other testing, from an INDEPENDENT source, not a seller?

As for your self appointed title of being "the most hated consumer by our industry", I think that is the furthest from the truthful fact as imaginable. The "Ivory Tower World" is certainly worthwhile knowing, but it has to logically and sensibly reconciled with the PRACTICAL WORLD. So you''re not hated, I think we have a totally different assessment of your "position" in our industry.

Rockdoc

 

[strmrdr]

Actualy Rockdoc that isnt a self proclained title it was given to me by a very prominant industry member of this board who shall remain nameless :}

"I am speaking specifically of the information that you specified getting... a machine that would grade polish in nano angstoms."

ok np :}

Today there may be very few that would be interested tomorrow who knows.

I was talking in general when I was talking about vendors resisting moving up the equipment ladder.
ROI is one of the reasons and my grandpaw didnt need one is the even bigger reason.
I would think that you would like one yourelf to go with the electron microscope you have mentioned you wanted???

the 25 were diamonds.
Iv been too busy buying bullets and beans and paying doctor bills to buy more.
They werent big enough to make it worth while running all the toys on.
But like I said my pocketbook is not the the limit :}

 

[adamasgem]

Now Here is a technical question regarding the modleing of the observational analyses that GIA conducted..
I think that the series of dome tests that GIA conducted was both innovative and interesting, and I''d like to get some input from GIA as to how they modeled the observations to generate the correlations that led to their adaptation of a 23 degree hemisphere with uniform illumination. YOU CAN''T MAKE that theoretical model with a lightbox illlumination.

In my technical opinion, the model for their observation is WRONG because

1) The (supposedly acrylic) domes are NOT diffuse reflectors UNLESS the insides of the domes were etched or coated with a white reflectace standard (like that made by Munsell), and I doubt they were

2) The 23 degree black is most probably not a 100% absorber, more like 95% as a guess from the pictures.

3) Backlighting with a light box, with a supposedly centered black holder for the stone and the 23 degree black aborber WILL NOT technically produce a uniform illumination from the white areas of the dome.

I believe you can consider any point on the light box as a point source, which, if you consider the light from that point spherically emenating from that point, will have intensity variations as 1/r*r, so it appears that if you analyse the first available reflections from the hemisphere will have stronger light intensity at the bottom of the hemisphere than at the edge of the black boundary.

If they, GIA, have modeled their hemispheres incorrectly, then their correlation analyses are very suspect.

I do NOT SEE how they, using a lightbox as the source (example in the picture), could produce the theoretical model they proposed and used for brightness.

Not only are the observers seeing direct backlighting from the lightbox as a high intensity "surround" or background if you look at technical CIE color adaptation models, the uniform intensity model is incorrect and will overweight the influence of low angle lighting..

Technical comments anyone out there?

 

[Serg]

re: Technical comments anyone out there?

I do not see good correlation between Fig 7( real light dome) and Fid 10 ( model light doom)

1) I do not see any track of 46 black head on dome on Fig7. Dome is semi transparence but track from Black head is absent
2) How had been dome illuminated from inside ? ("Area below girdle is dark"?)....

 

[adamasgem]

Date: 2/24/2006 6:07:50 AM
Author: Serg

re: Technical comments anyone out there?

I do not see good correlation between Fig 7( real light dome) and Fid 10 ( model light doom)

1) I do not see any track of 46 black head on dome on Fig7. Dome is semi transparence but track from Black head is absent

Sergey The picture of the observer was with a pure white dome (as an EXAMPLE), in the G&G issue they showed examples of some of the domes used, including, I believe, the 23 degree dome

2) How had been dome illuminated from inside ? (''Area below girdle is dark''?).... The light box illuminated the domes from the inside. I assume there was a smaller black disk inside the dome sitting on the light box on which the stone was placed, but have no idea what the size was.

 

[adamasgem]

Sorry to have confused or mislead anyone. This was the complete illustratration showing some of the domes GIA used. I clipped the observer to show the light box bottom illumination.

Again, I say, this was an innovative study, probably based on Al Gilbertsons work with EightStar with colored domes (prior to Al''s going to GIA), which I believe, tried to look at the relative faceup appearance of the diamond sets versus where the diamonds were collecting their light from. Al''s original concepts of looking at where diamonds recieve their light from, and presented at the GIA symposium in 1999, formed the basis for AGS''s work.

I think the correlations of their vast observational study may have been misleading and/or poor, because of the theoretical modeling done by others in the team. This theoretical modeling apparently (I''m not sure) assumed a uniform light intensity for any white areas of any dome that was lit from the inside by placing it on a lightbox, trying to make the dome(s) look like what is called an integrating sphere. I ASSUME this becuase of their final model.

Integrating spheres typically have one baffled hot spot of intense illumination, and the rest of the sphere is uniformly illuminated (at a lower intensity) because of the diffuse spectrally flat reflection within the sphere. They are quite expensive to coat with some variant of Barium Sulphate or Magnesium Oxide or sintered Teflon (PTFE), which are spectrally flat diffuse reflectors, and used in techncal measuremnt applications.

White acrylic domes are used in photography applications and can be ordered from companies like shown at http://www.globalplastics.ca/domes.htm . These domes are transluscent to opaque, depending on the thickness, and are not diffuse reflectors unless properly prepared inside. (I believe they should be lightly sanded inside). I don''t know whether or not the GIA domes were prepared as such, I hope they were. There is also the issue of non uniform spectral attenuation that may or may not have to be addressed, depending on the pigments used to tint the acrylic used to mold the domes.

The apparent translucency issue, as shown in the GIA example with the observer, may or may not have effected the attempt at uniform illumination in the GIA studies.

 

[belle]

what i notice about the example, is that the observer is looking through a dome that obviously has none of the patterning inside that they illustrate as having used. this may or may not be an issue, but it just goes to show that there are details entirely left out of what could (should) have been a solid, scientific test environment. such is not the case.

 

[adamasgem]

Date: 2/24/2006 2:18:27 PM
Author: belle
what i notice about the example, is that the observer is looking through a dome that obviously has none of the patterning inside that they illustrate as having used. this may or may not be an issue, but it just goes to show that there are details entirely left out of what could (should) have been a solid, scientific test environment. such is not the case.

Belle I believe you have made an incorrect interpretation.
GIA showed an observer looking through a unobscured dome, but correctly studied MANY dome configurations in an effort to understand the problem, which was what the effects on percieved brightness were as a function of where the light was coming from.
Their observational studies may or may not have other problems, but I believe the major "fault" appears to be in the "modeling" of those studies, and that opinion is based on their final theoretical diffuse illumination model overweighting low angle lighting.

If one looks at their CVE (common viewing environment DiamondDock(TM)) light box they are now trying to sell at $1600 or so, The most intense lighting comes from above with fluorescent tubes, and the reflection off of the gray background (whose reflectance I don't know, but my guess it is on the order of a neutral 50% to 70% reflector, although they don't say, I'll know better when I get to see on at a show) is of much lower intensity, and also assymetric.. entirely inconsistent with their "brightness" metric 23 degree obscured hemisphere.

If they are going to sell a high priced light box for viewing diamonds, then why isn't their cut grade based on viewing with such and environment??????????

 

[belle]

Date: 2/24/2006 3:48:40 PM
Author: adamasgem

Date: 2/24/2006 2:18:27 PM
Author: belle
what i notice about the example, is that the observer is looking through a dome that obviously has none of the patterning inside that they illustrate as having used. this may or may not be an issue, but it just goes to show that there are details entirely left out of what could (should) have been a solid, scientific test environment. such is not the case.

Belle I believe you have made an incorrect interpretation.
GIA showed an observer looking through a unobscured dome, but correctly studied MANY dome configurations in an effort to understand the problem, which was what the effects on percieved brightness were as a function of where the light was coming from.
Their observational studies may or may not have other problems, but I believe the major ''fault'' appears to be in the ''modeling'' of those studies, and that opinion is based on their final theoretical diffuse illumination model overweighting low angle lighting.

If one looks at their CVE (common viewing environment DiamondDock(TM)) light box they are now trying to sell at $1600 or so, The most intense lighting comes from above with fluorescent tubes, and the reflection off of the gray background (whose reflectance I don''t know, but my guess it is on the order of a neutral 50% to 70% reflector, although they don''t say, I''ll know better when I get to see on at a show) is of much lower intensity, and also assymetric.. entirely inconsistent with their ''brightness'' metric 23 degree obscured hemisphere.

inconceivable! thanks for clarifying marty. i really should leave the interpretation part to the pros.

 

[adamasgem]

Date: 2/24/2006 3:54:18 PM
Author: belle
inconceivable! thanks for clarifying marty. i really should leave the interpretation part to the pros.

Not necessarily.. There appear to be some "pros" over in Carlsbad who misinterpret (or interpret for their own convenience)just as easily as "novices".. There is an old saying about not seeing the forest because you are looking at the trees also...

 

[strmrdr]

Date: 2/24/2006 3:48:40 PM
Author: adamasgem

Date: 2/24/2006 2:18:27 PM



If they are going to sell a high priced light box for viewing diamonds, then why isn''t their cut grade based on viewing with such and environment??????????

Has it been proven that it wasnt?
What im having a problem with is no one knows.
There is a ton of speculation going on but little real info.
Which is GIA''s fault.
When one takes a bit of info from there and another bit from there and another from here they may not add up to the currect picture because you dont know where they fit.

 

[adamasgem]

Date: 2/24/2006 7:02:43 PM
Author: strmrdr

Date: 2/24/2006 3:48:40 PM
Author: adamasgem

Date: 2/24/2006 2:18:27 PM



If they are going to sell a high priced light box for viewing diamonds, then why isn''t their cut grade based on viewing with such and environment??????????

Has it been proven that it wasnt?
What im having a problem with is no one knows.
There is a ton of speculation going on but little real info.
Which is GIA''s fault.
When one takes a bit of info from there and another bit from there and another from here they may not add up to the currect picture because you dont know where they fit.

Well Go back and read the 2004 G&G article where they supposedly laid it on the line. Admitedly, everthing they are doing is not defined, but the basis for their brightness and fire metrics are stated there..

 

[BrianTheCutter]

Hello ladies and gentlemen. I have been out of the country but have been following conversations here. New thread today.

GIA EX Let the buyer beware. https://www.pricescope.com/community/threads/gia-ex-let-the-buyer-beware.41371/