The reason why GIA should add the SI3 grade

[Garry H (Cut Nut)]

@Rockdiamond @Wink @John Pollard @Garry H (Cut Nut) @Karl_K @david b

Re-reading some posts... we know that cut grade will be demoted if a stone exhibits what the GIA considers excessive brillianteering (and know that the GIA has little tolerance for it but that’s a different topic) - Cut grade affected by brillianteering...

1. If a stone has both proportions-based reasons to demote cut grade and “excessive brillianteering” (that would have been sufficient to drop cut grade without other proportions considerations) will Cut grade affected by brillianteering be noted on the report?

2A. Can “excessive brillianteering” cause cut grade demotion from all cut grades? Ie. Cut grade affected by brillianteering can be the cause of demotion from EX to VG. Can it cause demotion from VG to Good?

2B. Can “excessive brillianteering” cause a single-grade demotion only? (Ie. Wouldn’t ever be reason to drop cut grade from EX to Good).

I don’t want to deal with calling GIA and google isn’t answering

Hi Yssie, Yes GIA note Brillianteering. But not relevant in this case. The stone is GIA Good because of the combo of 40 and 40.2 crown and pavilion angle. Even with a 57% table this would be so
http://www.octonus.com/oct/mss/gia-ags.phtml
Add in the Thin to Thick girdle plus 61% table and we have other downgrade opportunities.

 

[bmfang]

Interesting read. The line about a SI2 stone needing to be eye clean is interesting given that there are a number of SI1 stones that us diamond tragic consumers find to be non eye clean.

As a consumer, what I would really like to know is what are the criteria that GIA use to determine SI1, SI2 and I clarity stones. But I suspect that GIA would want to charge me for that secret sauce in one of their courses...

 

[the_mother_thing]

If part of the SI2s are eye clean and part are not there is a visual difference between this SI2 or another SI2, the ones that are not eye clean should be SI3.

So at least if i offer a customer an SI2 I will not need to check if it is eyeclean

But GIA standards aren’t ‘eye clean’; they are determined with 10x magnification. So you’re suggesting not only adding a clarity grade, but also changing the methodology for how clarity is graded, it seems. And wouldn’t that also be just as subjective as doing so under magnification? If any change is to be made, perhaps it is becoming more strict on their criteria of what does/does not make a certain clarity grade that already exists vs adding a grade, changing the methodology, etc.

Forgive me, but as a consumer, I want my diamond dealer scrutinizing a prospective stone I am considering buying; not relying solely on what GIA says so it’s ‘one less thing he/she has to do’. I see that as a huge part of the value in purchasing from WF, HPD, IDJ, GOG, etc. - they do/will scrutinize a diamond with analysis imageryand expert-trained eyes and tell me what they see, if/how inclusions impact performance, etc. IMO they go above and beyond in customer service, and that’s why they are so highly regarded on here and why people recommend other prospective buyers to them.

 

[John P]

Hi John, my assessment was focusing on the pavilion reflection (which is only slightly affected by crown angle) because that was the easiest way to ID it was not the stone / cert. I was off by 0.25degrees. So not that bad in my view. You need to addd in the additional draft reflections.

You're right. The disconnect was a bad habit. Crown focus is my main use for recut-assessment. Tilt distorts that more than it does the good old reliable pavilion. It explains why your crown estimate was off by a mile - but you never even needed it.

And yes, a round is great, but I want the $5 so I can frame it

Fair enough. I'll even pin it to your chest.

 

[Rockdiamond]

As a consumer, what I would really like to know is what are the criteria that GIA use to determine SI1, SI2 and I clarity stones. But I suspect that GIA would want to charge me for that secret sauce in one of their courses...

This is a super common question and exactly at the core of consumer misunderstanding in my experience.
There's no "secret sauce".
Doing what it takes to become a GG ( taking the GIA courses, etc) will NOT qualify a person to be a diamond grader.
One needs to look at literally thousands of stones to develop the context to determine the dividing line between SI1 and SI2 ( for example)
And there is no hard line- the grades are subjective.
That's why one would need to look at so many stones to develop the ability to grade.

 

[John P]

But GIA standards aren’t ‘eye clean’; they are determined with 10x magnification. So you’re suggesting not only adding a clarity grade, but also changing the methodology for how clarity is graded, it seems. And wouldn’t that also be just as subjective as doing so under magnification? If any change is to be made, perhaps it is becoming more strict on their criteria of what does/does not make a certain clarity grade that already exists vs adding a grade, changing the methodology, etc.

Forgive me, but as a consumer, I want my diamond dealer scrutinizing a prospective stone I am considering buying; not relying solely on what GIA says so it’s ‘one less thing he/she has to do’. I see that as a huge part of the value in purchasing from WF, HPD, IDJ, GOG, etc. - they do/will scrutinize a diamond with analysis imageryand expert-trained eyes and tell me what they see, if/how inclusions impact performance, etc. IMO they go above and beyond in customer service, and that’s why they are so highly regarded on here and why people recommend other prospective buyers to them.

Regarding the subject topic, I think the two paragraphs above are key.

Eye-clean was not designed as a lab judgment. ‘Back in the day’ jewelry purchases were a matter of show & tell. Before internet-lookup, consumers learned about the Cs from their jeweler when seeing the stone. Eye-clean was self-evident, and the variability in SI-I clarity appearance gave jewelers the opportunity to romance individual stones by showing and explaining specifics and how the grade was earned. This wasn’t only designed for low clarity. The VVS tiers were designed to be romanced and explained in person, as added-value beyond naked eye distinction.

A half-century later things have changed. Reports are often seen by jewelers (and consumers) before the diamond is. Forward thinking sellers publish eye-clean standards and use them in communications. But that’s just the start. There are many details a grading report may not reveal. Per @the_mother_thing 's comments: At the end of the chain there’s no substitute for a great jeweler scrutinizing and clearly communicating all relevant details, as a decisive layer of protection for his or her clients.

 

[yssie]

Some input from GIA for anyone interested:

1. If a stone has both proportions-based reasons to demote cut grade and “excessive brillianteering” (that would have been sufficient to drop cut grade without other proportions considerations) will Cut grade affected by brillianteering be noted on the report?

No. The note is made only if painting/digging is the grade-determining factor.

2A. Can “excessive brillianteering” cause cut grade demotion from all cut grades? Ie. Cut grade affected by brillianteering can be the cause of demotion from EX to VG. Can it cause demotion from VG to Good?

In theory, yes, brillianteering could cause grade drop from VG or lower. In practice the rep couldn't think of a time she'd seen it.

2B. Can “excessive brillianteering” cause a single-grade demotion only? (Ie. Wouldn’t ever be reason to drop cut grade from EX to Good).

In theory, no, brillianteering could cause more than one grade drop. In practice the rep couldn't think of a time she'd seen it.

 

[gm89uk]

I also don't think eye clean should factor into clarity assessment. A hypothetical crystal hidden under the crown, or clearly visible under the table should receive the same clarity grade.

 

[Diamond Girl 21]

GIA has been softening standards lately. I have a real trouble finding decent eye-clean SI1 nowadays, and it wasn't like that just 10 years ago. Even many VS2 are like the past SI1, and I can't even order VS1 blind anymore.[/QUOTE



Wow!!! That's so interesting. I just received my GD from GIA in December and my instructor taught us very specific, tight guidelines. The stone in question would be probably be graded an I2 by me (provided it looks like this under 10X magnification), but I'm no expert...just merely more informed.

 

[blueMA]

@Diamond Girl 21 Having recently found an extremely rare amazing SI1 among the pool of terrible ones, I'm sure the differences in the grading margin is due to human perceptual variances, especially when separated by lab locations and continents.

 

[oldminer]

The degree of subjectivity we find in grading cannot be cured by our traditional grading methods. Grading by eye will always leave room for disagreement. Adding an additional grade will not be a cure for anything and likely would create even more problems as the number of grades increases while human perception remains fixed and incapable of our expectations of consistency and repeatability.

The cure would be properly programmed scientific methods using analysis of all the important aspects of grading but programmed into devices which have higher degrees of precision and repeatability than humans have. It has been done already, but the trade is far from anxious or excited by the prospect of grading without the occasional fortunate mistake. Kicking and screaming, the trade will eventually see how much more confident consumers will be about such a uniform and fair approach to ascertaining color and clarity grading. Once the consumer side of the equation becomes strong enough, there will be a rush to use well supervised equipment to analyze color and clarity grades. This can lead to far more consistent grading world-wide. I see such grading as a win for everyone.

 

[TreeScientist]

The degree of subjectivity we find in grading cannot be cured by our traditional grading methods. Grading by eye will always leave room for disagreement. Adding an additional grade will not be a cure for anything and likely would create even more problems as the number of grades increases while human perception remains fixed and incapable of our expectations of consistency and repeatability.

The cure would be properly programmed scientific methods using analysis of all the important aspects of grading but programmed into devices which have higher degrees of precision and repeatability than humans have. It has been done already, but the trade is far from anxious or excited by the prospect of grading without the occasional fortunate mistake. Kicking and screaming, the trade will eventually see how much more confident consumers will be about such a uniform and fair approach to ascertaining color and clarity grading. Once the consumer side of the equation becomes strong enough, there will be a rush to use well supervised equipment to analyze color and clarity grades. This can lead to far more consistent grading world-wide. I see such grading as a win for everyone.

I never understood why the top labs do not already use a machine for color-grading. Colorimeters that measure the absorbance of a particular wavelength or wavelengths (which would be blue absorbance for yellow-colored diamonds, which is why lower-colored diamonds loose some of their colored flashes. That is another tangent though ) are relatively cheap and very accurate. Have everyone use a colorimeter with a set of master standards supplied by a referencing agency, and then have each lab publish the brackets of absorption magnitude that they define as a "D" "E" "F" etc.

Why are we still relying on a human staring at a set of master stones and seeing where the stone being graded "fits the best" when an objective, precise machine-based method exists? That would eliminate all of the "AGS is softer than GIA on color" or subjective "This is a "high G"" nonsense from the discussion. And it would also eliminate the potential for human error and confounding variables, like the presence of fluorescence often resulting in diamonds being graded 1-2 color grades higher than their actual color grades:
https://www.pricescope.com/journal/blue-fluorescent-diamonds-color-grading-issues

Instead, list the letter grade and the percent absorption at different wavelengths of the colored light spectrum that each individual stone exhibits. Same could be done for quantifying fluorescence by the use of a bispectral fluorescence colorimeter.

But I'm sure there are industry forces at play that don't want this to happen... Same goes for the assessment of clarity, although that seems like it would be a bit more complicated and would necessitate some fairly complex algorithms and machine learning. Care to elaborate on how they've approached it in the past @oldminer? I'm genuinely curious.

 

[Rockdiamond]

Having recently found an extremely rare amazing SI1 among the pool of terrible ones,

Hi Blue- as a statement, this is a mischaracterization. It's not correct to assume the majority of GIA graded SI1 graded diamonds are terrible.
I do find that as time goes on, there are less eye clean ones for reasons of how the market works- but at this point in time, by no means are the majority of SI1 graded diamonds "terrible"

 

[Texas Leaguer]

I never understood why the top labs do not already use a machine for color-grading. Colorimeters that measure the absorbance of a particular wavelength or wavelengths (which would be blue absorbance for yellow-colored diamonds, which is why lower-colored diamonds loose some of their colored flashes. That is another tangent though ) are relatively cheap and very accurate. Have everyone use a colorimeter with a set of master standards supplied by a referencing agency, and then have each lab publish the brackets of absorption magnitude that they define as a "D" "E" "F" etc.

Why are we still relying on a human staring at a set of master stones and seeing where the stone being graded "fits the best" when an objective, precise machine-based method exists? That would eliminate all of the "AGS is softer than GIA on color" or subjective "This is a "high G"" nonsense from the discussion. And it would also eliminate the potential for human error and confounding variables, like the presence of fluorescence often resulting in diamonds being graded 1-2 color grades higher than their actual color grades:
https://www.pricescope.com/journal/blue-fluorescent-diamonds-color-grading-issues

Instead, list the letter grade and the percent absorption at different wavelengths of the colored light spectrum that each individual stone exhibits. Same could be done for quantifying fluorescence by the use of a bispectral fluorescence colorimeter.

But I'm sure there are industry forces at play that don't want this to happen... Same goes for the assessment of clarity, although that seems like it would be a bit more complicated and would necessitate some fairly complex algorithms and machine learning. Care to elaborate on how they've approached it in the past @oldminer? I'm genuinely curious.

GIA is already color grading certain subsets of stones by instrument only. Mainly smaller stones in the yellow hues without fluoro. I think you can look at that step in the same light as current autonomous driving. It's being rolled out very cautiously. But it is just a matter of time before most (but probably not all) color grading will be automated.

 

[Rockdiamond]

I agree with Bryan.
GIA is cagey in revealing exact methodology- but based on certain consistencies I find within Fancy COlor- and close to fancy color grading, I believe machines are definitely involved.

 

[Texas Leaguer]

Kudos to the sceptics!

Armchair quarterback here:
Let it be know that I was on Team Skeptic all along. I'm impressed by you guys. I mean us guys (and gals). No, not because of the advanced LP homework I did on DiamCalc. I subscribe to the KISS philosophy. The stone plot did not match the photo!
But I was reluctant to jump on @david b's life raft. I would like for him to survive that little glitch

Actually it turned out he stimulated quite the lively discussion here. Good going David!

Regarding Si3, I am staunchly in the "no" camp. Reading the report carefully can communicate much and convey whether a stone is likely to be a high or low Si2. Then of course inspecting it carefully, fills in the gaps inherent in the report.

You can think of the lower clarity grades as something akin to a clothing 'seconds rack'. There is everything there from small defects that nobody will ever see, to large ones that make the garment not fit at all, and everything in between. When shopping this broad category, you can find great bargains. It just takes more time and effort. You may have to kiss a lot of frogs to find your prince!

 

[blueMA]

Hi Blue- as a statement, this is a mischaracterization. It's not correct to assume the majority of GIA graded SI1 graded diamonds are terrible.
I do find that as time goes on, there are less eye clean ones for reasons of how the market works- but at this point in time, by no means are the majority of SI1 graded diamonds "terrible"

Sure we can disagree on the semantics but that's what I've seen in the last several months churning through all inventories of every single diamond vendors out there. It wasn't this hard just over a decade ago.

 

[Rockdiamond]

Sure we can disagree on the semantics but that's what I've seen in the last several months churning through all inventories of every single diamond vendors out there. It wasn't this hard just over a decade ago.

HI Blue- I can totally understand how looking online could give someone that impression.
If we're going by internet assessment we'll get incorrect results as compared to looking at actual diamond inventories, hands on, in person.
I'm basing my statements on hands on inspection of diamonds in the NY market.

 

[blueMA]

HI Blue- I can totally understand how looking online could give someone that impression.
If we're going by internet assessment we'll get incorrect results as compared to looking at actual diamond inventories, hands on, in person.
I'm basing my statements on hands on inspection of diamonds in the NY market.

Please check out this post by @John Pollard
https://www.pricescope.com/communit...uper-ideal-diamond.174235/page-2#post-4323297

"Ten years ago we found more acceptable crystals in lower clarities. We crafted abundant SI1-SI2. We even polished a few I1s, although that seems like forever-ago. The main challenge wasn't fundamental transparency then, it was planning the orientation of grade-setting inclusions to keep the diamond eye-clean. Today our rejection rate is higher across all categories and finding transparent, clean SI2 candidates has become painfully rare."

 

[Rockdiamond]

Hi Blue- check out my posts as well- John and I operate in different markets- and look at different goods.

For readers- having a variety of seasoned tradespeople give a more comprehensive view.
You mentioned you'd seen it- so it sounded like you'd personally inspected the diamonds.
FYI DBL was a CBI dealer 10 years ago as well.

 

[blueMA]

Hi Blue- check out my posts as well- John and I operate in different markets- and look at different goods.

For readers- having a variety of seasoned tradespeople give a more comprehensive view.
You mentioned you'd seen it- so it sounded like you'd personally inspected the diamonds.
FYI DBL was a CBI dealer 10 years ago as well.

I've read your posts David, and the fun quarrel between you and @Garry H (Cut Nut) on other thread.

The bottom line is that it's much harder to find a good SI stone nowadays, and I often see pretty bad VS2s with compromised transparencies as of recent. This is not just my personal observation - this is being observed by many others on PS as well.

 

[Rockdiamond]

Thank you Blue- I like your posts too

Here's the issue- PS can become an echo chamber. So one person- or a few people have a bad experience with an SI1 stone- it gets repeated and people start to take it as gospel. But it all started with just a few people's opinions- and the opinions may have been formed from a very limited data set.
I have no reason whatsoever to doubt my friend John's experience looking at crystals. In general, cutting round diamonds is a different ball of wax than cutting fancies- and even more so if one needs to buy crystals for super ideal RBC's. So we will see this from different perspectives.
I do agree that there's a smaller percentage of eye clean SI1 diamonds today. But I do not agree at all that great looking SI1's are rare. And- I find this to be a very important point because understanding SI stones is very important to many buyers.
I still find that a lot of folks want value.

 

[Texas Leaguer]

Thank you Blue- I like your posts too

Here's the issue- PS can become an echo chamber. So one person- or a few people have a bad experience with an SI1 stone- it gets repeated and people start to take it as gospel. But it all started with just a few people's opinions- and the opinions may have been formed from a very limited data set.
I have no reason whatsoever to doubt my friend John's experience looking at crystals. In general, cutting round diamonds is a different ball of wax than cutting fancies- and even more so if one needs to buy crystals for super ideal RBC's. So we will see this from different perspectives.
I do agree that there's a smaller percentage of eye clean SI1 diamonds today. But I do not agree at all that great looking SI1's are rare. And- I find this to be a very important point because understanding SI stones is very important to many buyers.
I still find that a lot of folks want value.

This may sound like I am contradicting myself from some other comments I made in the other thread about transparency problems, but I agree with David. In the broad market, it is not rare to find nice Si1's. There are plenty of decent stones in circulation that offer appealing value.

You have to remember that dealers who buy on site and/or have production agreements with manufacturers tend to cull out many of the better stones. Often what you find in the online virtual market are stones not grabbed as they come out of production. And, as a prosumer, when you combine looking for eye-clean stones with no issues with HCA under 2, and LP images that show great optics, well you can see where the needle starts to get buried under a whole lot of hay.

I am personally not convinced that what we are seeing is truly a result of rough having diminished in quality, as much as it is dramatic changes in the marketplace propelled by e-commerce, much greater emphasis on imaging, and an increased sensitivity to light performance deficits in diamonds cut for elite optics.

 

[Diamond Girl 21]

@Diamond Girl 21 Having recently found an extremely rare amazing SI1 among the pool of terrible ones, I'm sure the differences in the grading margin is due to human perceptual variances, especially when separated by lab locations and continents.

I'm sure that's certainly part of it as grading/viewing by a person has to be somewhat subjective. I've never worked in a lab, although I would love to, but I believe GIA uses 3 graders to make sure there is a consensus. Does anyone know if this is correct? And we all know how stones with the same grade can look very different. It's sort of a range with different criteria in my humble opinion. For example, a great SI1 vs an SI1 that's almost an SI2.

Congratulations on finding a great stone.

 

[blueMA]

But I do not agree at all that great looking SI1's are rare. And- I find this to be a very important point because understanding SI stones is very important to many buyers.
I still find that a lot of folks want value.

Agreed - I don't like to waste money for something graded higher when it doesn't contribute to real life performance

You have to remember that dealers who buy on site and/or have production agreements with manufacturers tend to cull out many of the better stones. Often what you find in the online virtual market are stones not grabbed as they come out of production. And, as a prosumer, when you combine looking for eye-clean stones with no issues with HCA under 2, and LP images that show great optics, well you can see where the needle starts to get buried under a whole lot of hay.

Also agree to an extent - but I've also been rejecting too many VS2 stones nowadays for clarity/transparency, which was very rare in the past.

 

[Rockdiamond]

I am personally not convinced that what we are seeing is truly a result of rough having diminished in quality, as much as it is dramatic changes in the marketplace propelled by e-commerce, much greater emphasis on imaging, and an increased sensitivity to light performance deficits in diamonds cut for elite optics.

We agree Bryan- my feeling is that it's changes in the way people buy diamonds that are changing the percentages. The largest internet sellers experience very high return rates.
The eye clean stones are kept, while those "un eye clean" stones get dumped back into the pool.
Plus, buyers that are actually looking at the SI goods are also filtering out a percentage of the eye clean SI stones.
10 years ago, it's likely that the higher percentage of stones bought in B&M's produced different effects on the pool of goods.

Also agree to an extent - but I've also be rejecting too many VS2 stones nowadays for clarity/transparency, which was very rare in the past.

Is the rejection based solely on internet imagery?

Garry and I have been going back and forth on assessing dullness using ViBox imagery. It's an amazing photography system.
Yet, personally, I would not feel comfortable assessing the transparency of a diamond from even the best imagery.

 

[Texas Leaguer]

Agreed - I don't like to waste money for something graded higher when it doesn't contribute to real life performance

Also agree to an extent - but I've also been rejecting too many VS2 stones nowadays for clarity/transparency, which was very rare in the past.

I don't at all doubt that observation. I just think the reason that is true probably has more to do with changes in the marketplace than lab grading trends or the quality of rough coming out of the ground.

 

[Diamond Girl 21]

Interesting read. The line about a SI2 stone needing to be eye clean is interesting given that there are a number of SI1 stones that us diamond tragic consumers find to be non eye clean.

As a consumer, what I would really like to know is what are the criteria that GIA use to determine SI1, SI2 and I clarity stones. But I suspect that GIA would want to charge me for that secret sauce in one of their courses...

There are specific guidelines in GIA education material. Location, relief, number, size and type all in relation to the size of the stone viewed under 10X magnification.

 

[blueMA]

Yet, personally, I would not feel comfortable assessing the transparency of a diamond from even the best imagery.

This is true. My VS1 stone I ended up returning looked crystal clear with not a single spot on 40x 360 video, and I also had two people vet it before shipping - but obviously this was an example of a bizarre unusual stone.

I've exhausted all local retail stores with carried inventories (absolutely terrible), had 8 stones shipped (mostly from NY), and I ended up rejecting them all. Then I turned to online, and mostly churned through the stones with photos and 360 videos, but also inquired about many stones without photos/videos when they had the proportions I was seeking. It turned out most of the stone without photos had reasons why not...

In the past, it took me only a few days to find what I was looking for. This time around, it took me several months.

 

[John P]

There are specific guidelines in GIA education material. Location, relief, number, size and type all in relation to the size of the stone viewed under 10X magnification.

Spot on. But what lies beyond 10X?