Clarity grading question?

[yssie]

Can one of our tradespeople elaborate on how clarity grading is done - specifically, does someone, at some point in the process, eyeball the stone to judge if the through-the-loupe grading is reasonable/accurate/acceptable?

The labs' websites make it very clear that all grading is done with a 10x loupe, and that all potential grade assignments - Very Very Slightly, Slightly Included, etc. are defined by visibility through a 10x loupe. We know that what is seen through the loupe does not necessarily correlate to visibility w/ the naked eye - 'good' vs 'bad' SIs. But I have also read on PS that a stone with an inclusion under the table might be given a lower clarity grade than another stone with that same inclusion off to the side under the crown, which seems to imply that real-world visibility does have a part in the grading procedure?

Would appreciate some insight into this.

 

[Rockdiamond]

Great questions yssie!

Clarity grading is based on the physical existence of imperfection. This is quite different from the visibility of said imperfection.
So, it really does not matter at all how the stone looks to the naked eye- in fact, how it looks to the naked eye is irrelevant to an accurate clarity grade.
This is a very good point- and most frequently understood.
"Oh, I can see all Si2 imperfections"
or
"VS diamonds are always eye clean"
Both hypothetical statements have no basis in fact. Nor would any statement about location of imperfection affecting the clarity grade- that too is irrelevant.
Even I1 diamonds can be completely eye clean.

 

[Lula]

Great questions yssie!

Clarity grading is based on the physical existence of imperfection. This is quite different from the visibility of said imperfection.
So, it really does not matter at all how the stone looks to the naked eye- in fact, how it looks to the naked eye is irrelevant to an accurate clarity grade.
This is a very good point- and most frequently understood.
"Oh, I can see all Si2 imperfections"
or
"VS diamonds are always eye clean"
Both hypothetical statements have no basis in fact. Nor would any statement about location of imperfection affecting the clarity grade- that too is irrelevant.
Even I1 diamonds can be completely eye clean.

Interesting topic, yssie.

So, RD, would it be safe to say that the clarity grade is given to simply mark the presence of inclusions (and to note the type and location of those inclusions in/on the stone) rather than to provide any information about the effect those inclusions have on the appearance or performance of the stone? Hope that makes sense.

 

[Rockdiamond]

Yes Lula!
GIA reports are actually quite clinical.
Although we use them to determine the value of stones, this must be done looking at the stone and report- the GIA report by itself does not give enough information to make meaningful assessments of clarity.

In fact, the plot and and description of the clarity characteristics on a GIA report often times creates more confusion than clarity of understanding ( pun intended)

The reason: It's virtually impossible to accurately convey an imperfection's affect on a stone on a 2d diagram

 

[Stephan]

Great original post, great replies!
Thank you!

 

[yssie]

I see! Thank you so much David, it was a question I'd never quite been able to put words to


Lula, I see what you are saying.

Just to be redundant and re-clarify then,
Slightly Included means there are imperfections that are easily seen through the 10x loupe. But, the given clarity grade says nothing whatsoever about the 'strength of visibility' through that 10x loupe, for lack of better wording. And the given grade definitely says nothing about - and is not based on - 'strength of visibility' w/ the naked eye, these are subjective judgments that we make (and quite possibly wrongly, if we try to use the 'existence' plots to determine 'visibility').


This has been enlightening!

 

[Jim Summa]

Hi Yssie,

I learned clarity grading in 1980 at GIA when it was still in Santa Monica...the diamond course was 2 months long and the instructors were constantly repeating to the class to "just look at the stone". At this time a SI2 had better be eyeclean and an SI1 MAY show an inclusion when viewed thru the Pavilion.
Location was stressed in clarity grading. The example I remember was on the VVS grades and that a couple (2) of tiny included crystals or pinpoints in the center of a stone would be graded a VVS2 when the same type of inclusion, off to the side, would get a VVS1.

Now, this was a while ago and things have changed over the years....but still I would be surprised if the GIA staff isn't still harping "just look at the stone " to each class that takes the diamond course.

Something you might find interesting is AGSL discussed using a blue marker on their reports for eye visible inclusions this year...it was voted down.

 

[yssie]

Jim - thanks for sharing your experience here!


But... hmmm.

This seems starkly different to the scenario David shared earlier. Quick q -when you say "just look at the stone", do you mean through a loupe or w/ just your eyes?

Do you think the grading course has changed to become more clinical over the years - where do you think the disconnect is? To the consumer clarity grading is such an opaque thing! How to reconcile the descriptions of location differences, questions of eyeclean, etc. and the issue of existence/visibility is exactly what I'd like to hear more about.


AGS - now that is a forward concept I must confess I am unsurprised that such a radical idea was turned down, though it would've been - at the very least interesting to see it play out in the market...

 

[Jim Summa]

Yssie,
We were students looking at diamonds (with microscopes) trying to understand the nuances that are being discussed in this thread.
An example that I remember at the time was a stone that appeared flawless...but had poor transparency. It was easier to see by just looking at the stone, the milkiness was pretty easy to see just using your eyes but something that we were overlooking by depending on the microscope. This stone was graded an I1.

I am afraid I just can't give an answer about how the GIA course has changed, or more specifically if it has become more clinical. When I took it Santa Monica was the only campus offered and now they are all around the world. So, maybe they are different. I have asked a more recent grad about how they are approaching/teaching cut more then anything else. On clarity grading, I think the SI grades aren't quite as strict as in 1980.

Something I will tell you about clarity grading that everyone who has been around awhile knows or understands and is often mentioned on Pricescope is that as the size of the stone increases the grading changes. I think it becomes a little generous, which, I think confuses the consumer. I have had, at times, a heck of a time trying to explain this to a customer. If you are looking at a stone before you send it to the lab you learn to take this into consideration.

Yssie, When you call the blue marker a Radical Idea I think you are sounding alot like a jeweler!

 

[yssie]

Yssie,
We were students looking at diamonds (with microscopes) trying to understand the nuances that are being discussed in this thread.
An example that I remember at the time was a stone that appeared flawless...but had poor transparency. It was easier to see by just looking at the stone, the milkiness was pretty easy to see just using your eyes but something that we were overlooking by depending on the microscope. This stone was graded an I1.

Honestly, a big part of me is comforted to hear that there was (and maybe still is) some checking of reality in the grading, wherever in the process it happened, "officially sanctioned" or not.
Another big part is wondering how far the 'spill-over' should go - and if things aren't shifting toward 'clinical' as David describes to start addressing this - say, clarity and light output are distinct in reporting, when technology catches up and effects of inclusions on performance can be accurately measured should cut or clarity grade consider this?.. But that's a question for another time.

I am afraid I just can't give an answer about how the GIA course has changed, or more specifically if it has become more clinical. When I took it Santa Monica was the only campus offered and now they are all around the world. So, maybe they are different. I have asked a more recent grad about how they are approaching/teaching cut more then anything else. On clarity grading, I think the SI grades aren't quite as strict as in 1980.

Something I will tell you about clarity grading that everyone who has been around awhile knows or understands and is often mentioned on Pricescope is that as the size of the stone increases the grading changes. I think it becomes a little generous, which, I think confuses the consumer. I have had, at times, a heck of a time trying to explain this to a customer. If you are looking at a stone before you send it to the lab you learn to take this into consideration.

Some time ago my jeweller showed me a 4.5ct RB that GIA had graded SI1 (200. My goodness, it had a white crystal easily half the size of a penciltip eraser right smack on top of one of the (thick!) mains, it was terribly visible In any case, he told me that grading is taught on 0.5ct stones, and that grading of larger stones is somewhat more generous as you say, but that there is no universal published metric to define this sliding scale by. As far as I know this is still the case, and it's a matter of seeing enough stones to "get the feel for it" - it would be nice if someone, somewhere, would put it into words and make it public!

Yssie, When you call the blue marker a Radical Idea I think you are sounding alot like a jeweler!

::snort::

 

[Lula]

Thanks, David and Jim for your insight and comments on this thread. Of all the C's, I think clarity is the toughest to decipher. A diamond buyer needs to know what each of the inclusions looks like; how they impact the structural integrity of the stone; how do you translate what you're seeing under a loupe or a gemscope into real-world performance/visual appearance, etc. And, perhaps most important, how do you feel about *knowing* the inclusions are there, even if you can't see them (mind clean). Plus, humans grade color and clarity, and mistakes are made; lab standards change over time, etc. Given all this, it's extremely hard to advise consumers about what's best for their eyes/preferences.

That's why I think it's important to work with a trusted vendor* who has seen a variety of stones over his/her career. That's where you start; however, I do believe a person has to live with the stone for at least a week, waiting for the "rush" to wear off, and view it under many lighting conditions and angles. And that's where a good return/exchange/trade-up policy is invaluable.

I do think consumers who are not experienced and/or not sure of what they want in color and clarity need to be willing to order a stone, live with it (perhaps have it appraised by an independent appraiser) and be willing to send it back if they are not satisfied with it. I know this involves extra time, shipping costs, etc., but as someone who lives in a city where well-cut stones are not readily available for comparison, and as someone who cannot accurately assess anything under those &&%%^^**& jewelry store lights, the only way I could make a decent decision about the 4 C's was to work with a vendor who provides not only photos and IS, ASET, etc., but also made videos of stones for me so I could compare, and, finally, has liberal return and upgrade policies in case the diamond is "not quite what I wanted."

*not the dude working Christmas season at Jared's!

 

[yssie]

Thanks, David and Jim for your insight and comments on this thread. Of all the C's, I think clarity is the toughest to decipher. A diamond buyer needs to know what each of the inclusions looks like; how they impact the structural integrity of the stone; how do you translate what you're seeing under a loupe or a gemscope into real-world performance/visual appearance, etc. And, perhaps most important, how do you feel about *knowing* the inclusions are there, even if you can't see them (mind clean). Plus, humans grade color and clarity, and mistakes are made; lab standards change over time, etc. Given all this, it's extremely hard to advise consumers about what's best for their eyes/preferences.

That's why I think it's important to work with a trusted vendor* who has seen a variety of stones over his/her career. That's where you start; however, I do believe a person has to live with the stone for at least a week, waiting for the "rush" to wear off, and view it under many lighting conditions and angles. And that's where a good return/exchange/trade-up policy is invaluable.

I do think consumers who are not experienced and/or not sure of what they want in color and clarity need to be willing to order a stone, live with it (perhaps have it appraised by an independent appraiser) and be willing to send it back if they are not satisfied with it. I know this involves extra time, shipping costs, etc., but as someone who lives in a city where well-cut stones are not readily available for comparison, and as someone who cannot accurately assess anything under those &&%%^^**& jewelry store lights, the only way I could make a decent decision about the 4 C's was to work with a vendor who provides not only photos and IS, ASET, etc., but also made videos of stones for me so I could compare, and, finally, has liberal return and upgrade policies in case the diamond is "not quite what I wanted."

*not the dude working Christmas season at Jared's!

Completely agreed, Lula - especially your first paragraph. I definitely think clarity is most difficult to translate from the strict lab definitions to real-world consumer concerns.

 

[Rockdiamond]

Hi Yssie,

I learned clarity grading in 1980 at GIA when it was still in Santa Monica...the diamond course was 2 months long and the instructors were constantly repeating to the class to "just look at the stone". At this time a SI2 had better be eyeclean and an SI1 MAY show an inclusion when viewed thru the Pavilion.
Location was stressed in clarity grading. The example I remember was on the VVS grades and that a couple (2) of tiny included crystals or pinpoints in the center of a stone would be graded a VVS2 when the same type of inclusion, off to the side, would get a VVS1.

Now, this was a while ago and things have changed over the years....but still I would be surprised if the GIA staff isn't still harping "just look at the stone " to each class that takes the diamond course.

Something you might find interesting is AGSL discussed using a blue marker on their reports for eye visible inclusions this year...it was voted down.

Jim, all due respect, but extensive practical experience would make me disagree with this point.
I've seen plenty of eye clean I1's, and non eye clean VS2's ( although, not so many of those).

I've got a friend who was an instructor over at GIA until last year- I'll ask him current doctrine.
But as I mentioned, my practical experience, looking at thousands of GIA graded stones, say different.

 

[Jim Summa]

Hi David,
My Diamond instructor at GIA was a great teacher named Jim Lucey. He had a passion for teaching about diamonds that I thought could never be rivaled until I discovered this forum.
Perhaps your friend over at GIA has heard of "Sir James of Lucey" which was his nickname when the institute was still located in Santa Monica. If not there are a couple of pages (187-18 written about him in "Legacy of Leadership" a book about the history of GIA by William George Shuster.
This book was given to me when I was elected into the American Gem Society (AGS), its a very good read.

Something I have never seen discussed, (or have missed) is any imput from students currently enrolled in Diamonds (or any of the other classes)at GIA.
What I think they could add to this thread is what you already know, and that is by studying lots and lots of diamonds (and that yeah its can be pretty hard) you will develop the feel and confidence for accurate and consistent clarity grading.

 

[yssie]

I just called GIA labs to clarify a clarity question in another thread, and thought I'd settle some of these debates also, if anyone uses this thread for reference:


1. Right now the "grade-setting" worst inclusion is listed first, and inclusions are listed from most to least severe through the loupe

2. Right now clarity grading is strictly through the 10x loupe, no naked-eye inspections anywhere in the process. The inclusion plot is just a road map - tells you nothing about real-world severity or 'strength of visibility' of inclusions - just where they are in the stone, or in the case of feathers how far they stretch, etc.


ETA: asked AGS too, same deal

 

[Rockdiamond]

Thanks Yssie!!

But specifically- did you ask them about the location issue?

 

[yssie]

Hi David - I did ask GIA that specifically too, and it apparently *can* depend on where it is. I copied my post from another thread and forgot to include it! They apparently grade five indicators (I'm remembering Jim from JA gave this list in another thread some time ago)
-nature
-size
-relief
-location
-number
and a stone w/ a given inclusion off to the side, near the girdle, may be given a higher clarity grade than another stone w/ the same inclusion under the table in a high-relief area. But it depends.

I am admittedly not so good with It Depends considerations


ETA all five are considered simultaneously, not in any hierarchy*

 

[Tom Gelb]

What I think they could add to this thread is what you already know, and that is by studying lots and lots of diamonds (and that yeah its can be pretty hard) you will develop the feel and confidence for accurate and consistent clarity grading.

Hello Everyone,

Just to lend a graders perspective here, when I was first training to be a grader at the GIA in the early 1990's my instructor and the lab director at the time discussed how long it took to really get a handle on clarity grading. They said if someone was very good that it took about 1-2 years at the lab. This translates to between 10,000 and 20,000 diamonds graded. There are many factors to get a handle on, and it just takes a very long time to become aligned with the other graders in the lab. I specifically remember getting 15 of my first 17 clarities wrong, that was a bummer. So my advice is to see as many graded diamonds as possible, it is really the only way to get good at grading. Remember it is not a science and cannot be learned from books only. It is a skill that takes a very long time to master.

Good luck

 

[yssie]

What I think they could add to this thread is what you already know, and that is by studying lots and lots of diamonds (and that yeah its can be pretty hard) you will develop the feel and confidence for accurate and consistent clarity grading.

Hello Everyone,

Just to lend a graders perspective here, when I was first training to be a grader at the GIA in the early 1990's my instructor and the lab director at the time discussed how long it took to really get a handle on clarity grading. They said if someone was very good that it took about 1-2 years at the lab. This translates to between 10,000 and 20,000 diamonds graded. There are many factors to get a handle on, and it just takes a very long time to become aligned with the other graders in the lab. I specifically remember getting 15 of my first 17 clarities wrong, that was a bummer. So my advice is to see as many graded diamonds as possible, it is really the only way to get good at grading. Remember it is not a science and cannot be learned from books only. It is a skill that takes a very long time to master.

Good luck

Thanks Tom.

In the actual practice of it, I agree - it's rather like becoming a good cook: I can follow my grandmother's recipes to the letter and still not wind up with anything of her calibre, because of those "stir until thick, like porridge" and "rolling boil for three minutes" steps - what sort of porridge? When exactly does a rolling boil start?

There is, however, IMO no reason that GIA's and AGS' consumers should not be privy to those recipe books, even if they are unable to actually practice with them. I was happy to find that the labs were very willing to share this information with me by phone.

 

[Rockdiamond]

Experience- that's really they key.
Along with desire.
I have no doubt that many of the regulars here on PS are actually far better prepared to become graders than a fair percentage of newly graduated GIA GG's.

Sad to say, but we've interviewed quite a few for open positions here that reflected poorly on the education GIA is providing.

After the following conversation, I called GIA to verify that the applicant had indeed, passed the GG course.
I had a diamond graded L, Light Brown" by GIA, and asked this new GG to enter into our system.
I specifically instructed the applicant to take specific note of the color when entering into the system.
When I checked the work, the stone had been entered as "L Color"- no mention of the light brown on the GIA report.

"Excuse me _____", I said. " DId you notice that GIA graded this 'L color Light Brown'?
By the way, did you study any fancy colors at GIA?"

"No", answered the applicant. "Only white diamonds, like A, B, and C colors."
"WHAT?"
" You know, white diamonds"
"Don't you mean D-E-F colors?"
"Oh yeah"

Even the most basic tasks- such as how to handle a diamond properly- and fold the parcel paper- are not covered in the GIA curriculum.
It's merely a starting point.

 

[druidtime]

I'm rather new here, but i'll give it a shot.

"All diamonds are graded under a microscope"

I was told this by a jeweler one time. I believe this to be true.

It seems that the reason why the larger stones are given more leeway as far as inclusions go is because the graders grade the size of the inclusion relative to the size of the stone.

If we imagine the (geometric) volume of the stone itself, we would know that the volume would increase with physical size of the stone. As the size of the stone increases, an inclusion that would be subjectively considered a 'minor' flaw (VS range) can become more visible as carat size increases. OR, as the size of the stone increases, then the larger the inclusion can be to be considered having a 'minor' impact on the stone itself.