Can you see the difference between "Good" and "EX" polish and Symmetry? Any personal experiences?

[Rockdiamond]

HI Everyone,
Can the difference between "Good" and "Excellent" on the polish and symmetry be seen with the naked eye?
If you have personal experience with this, I''d love to hear it!

 

[John P]

In a study some time ago the GIA found naked eye experts who could sometimes tell the difference between good and VG symmetry. For me girdle thickness variations wide enough to reduce a diamond to G are spottable without magnification. And in a 2007 GIA workshop I graded ''good'' symmetry examples (RB) where I could see facet symmetry variations (non-ptg/misshapen) - but I spotted them with a loupe first.

Polish depends on how much, where, what lighting and what scrutiny. Even the GIA lab manual states polish other than EX "might affect luster seen by unaided eye." If your question was the difference between VG and EX it would be easy for me to answer based on personal experience, as I don''t believe I''m capable of telling that difference with the naked eye. Maybe not G either (?) but that brings me back to the beginning of the paragraph.

I think of polish like the paint job on a car. Ideal/EX can be compared to the finest paint job possible, no inconsistency even with your nose up to the paint. VG and G may mean minor blemishes...imagine the paint job more grainy or rough in places...but seen from the sidewalk you won''t necessarily notice the difference.

 

[Rockdiamond]

Thanks John!
Good point about the girdle- as you know, I'm a girdle freak too ( umm, that didn't sound right did it?)


Regarding the GIA manual's statement about "might affect luster"- have you ever heard of a person being able to spot the difference naked eye- under any lighting?

Of course, regular readers probably know how I feel about this part.
I've never been able to see the minor aspects that would cause GIA to downgrade a stone from EX to VG or G on polish without the aid of a loupe- and actually never heard of a case where someone could.
That's why I'm really curious about the subject.

 

[strmrdr]

A lot of times with step cuts.
I saw missed meet points on the pavilion looking through the table on gia graded G symmetry emerald and asscher cuts more than once.


less so with RBs but a few times I could.

Good polish I could sometimes find by eye when looking for it.
Again much more often on step cuts

It all depends on which facets are affected,the extent of the variation, the size and shape of the diamond.

My opinion is:
GIA VG is safe
GIA G needs to inspected with a critical eye looking for issues.

 

[Rockdiamond]

Date: 7/6/2009 6:22:27 PM
Author: strmrdr
A lot of times with step cuts.
I saw missed meet points on the pavilion looking through the table on gia graded G symmetry emerald and asscher cuts more than once.


less so with RBs but a few times I could.

Good polish I could sometimes find by eye when looking for it.
Again much more often on step cuts

It all depends on which facets are affected,the extent of the variation, the size and shape of the diamond.

My opinion is:
GIA VG is safe
GIA G needs to inspected with a critical eye looking for issues.

Hi Storm,
In terms of symmetry, I believe you''re saying you have seen step cuts where the reason for the Good", versus the "EX" were apparent naked eye.
I have also been able to see that.

When you were able to spot "good" polish, what specifically did you find?
Were there visible flaws in the polish? What type?
I''m asking as I''m genuinly curious about your experience.

I have never been able to spot anything like that in a GIA G stone- even when I was a young pup, I needed a loupe to see individual facets'' polish in detail.
Large abrasions, like on older stones, maybe- but that sort of thing would not garner a G grade on polish from GIA.

 

[strmrdr]

Yes we agree on symmetry.

Finding polish errors by eye is fairly hard, surface graining is often easier to see.
The key is to look across the facets and get the light to hit them just so.
How they looked varied, some had tiny groves others looked slightly frosted or foggy.
The diamond also had to be very clean because sometimes it turned out to be something on the diamond.

 

[John P]

Date: 7/6/2009 6:06:02 PM
Author: Rockdiamond
Thanks John!
Good point about the girdle- as you know, I'm a girdle freak too ( umm, that didn't sound right did it?)

Some of the regulars complain about "brutal" girdles.

Regarding the GIA manual's statement about 'might affect luster'- have you ever heard of a person being able to spot the difference naked eye- under any lighting?

Surface graining - see Strm's post. In the same way, when polish lines are heavy enough to be 'drag lines' they can show in certain lighting. Or if you have a nick that's more like a chip an observer can use reflected light to spot it the same way a clarity grader would. Like I said above, it depends on how much, where, what lighting and what scrutiny.

Most of these occasions were in grading-specific workshops. I've also seen it among diamantaires working to make purchase decisions (like, could this GIA diamond be graded an AGS Ideal?) so things were being severely scrutinized, but I'd have to say it's possible if you look around hard enough.

With that said, I think GIA made a smart decision in terms of grading round brilliants: They allow polish & symmetry grades of EX and VG to qualify for an overall cut grade of Excellent. In terms of human vision and practicality this makes sense to me.

 

[oldminer]

Excellent is a very narrow grade. Very Good is a reasonably narrow grade, too. Good is a far broader grade.

I believe than many of us could tell the difference from a low good to a very good or excellent grade stone with the naked eye and that few of us could tell good/very good borderline stones from one another. This is because "good" has much more range. So the end result is that sometimes we might be able to see with the naked eye that a diamond is only "good" pol or sym and other times we might not be able to tell. I think we''d have a similar problem of where "fair" becomes "good", too doing it without magnification.

 

[Rockdiamond]

I really should have added the qualifier "without a loupe" to the subject line......

John- what I''m saying is that you and I - and I''m sure Storm and many other readers, would be able to find to find the reasons GIA downgraded many stones by using a loupe. Of course in many cases the difference between EX and G is extremely difficult to see even with a loupe, for a trained observer.

My point is that the grade differences between GIA and EX-Good ( for polish specifically) are more like those between IF and VVS2.

There''s a difference between an EX and Good, but the percentage of cases where such grades are distinguishable by eye is negligible.

 

[John P]

Date: 7/6/2009 7:31:21 PM
Author: oldminer
Excellent is a very narrow grade. Very Good is a reasonably narrow grade, too. Good is a far broader grade.

I believe than many of us could tell the difference from a low good to a very good or excellent grade stone with the naked eye and that few of us could tell good/very good borderline stones from one another. This is because ''good'' has much more range. So the end result is that sometimes we might be able to see with the naked eye that a diamond is only ''good'' pol or sym and other times we might not be able to tell. I think we''d have a similar problem of where ''fair'' becomes ''good'', too doing it without magnification.

Good overview Dave.

 

[strmrdr]

Date: 7/6/2009 7:37:19 PM
Author: Rockdiamond
I really should have added the qualifier 'without a loupe' to the subject line......


John- what I'm saying is that you and I - and I'm sure Storm and many other readers, would be able to find to find the reasons GIA downgraded many stones by using a loupe. Of course in many cases the difference between EX and G is extremely difficult to see even with a loupe, for a trained observer.


My point is that the grade differences between GIA and EX-Good ( for polish specifically) are more like those between IF and VVS2.


There's a difference between an EX and Good, but the percentage of cases where such grades are distinguishable by eye is negligible.

That is false.
You said by eye and I answered by eye.
With a loupe I could find it all the time..
A significant part of the time I could find it without a loupe in step cuts and could find it by eye in RBs

 

[Moh 10]

edit
Ferget it.
What's the point.

 

[Rockdiamond]

Date: 7/6/2009 7:31:21 PM
Author: oldminer
Excellent is a very narrow grade. Very Good is a reasonably narrow grade, too. Good is a far broader grade.
I agree with the above part. Just as VVS1 is narrower than VVS2 as a grade.

I believe than many of us could tell the difference from a low good to a very good or excellent grade stone with the naked eye and that few of us could tell good/very good borderline stones from one another. This is because ''good'' has much more range. So the end result is that sometimes we might be able to see with the naked eye that a diamond is only ''good'' pol or sym and other times we might not be able to tell. I think we''d have a similar problem of where ''fair'' becomes ''good'', too doing it without magnification.

I disagree with the underlined section. If a stone is graded fair, that''s when you would be more likely you be able to see why naked eye.

I also disagree that many could see the specific facets, or reasons why a stone was Good ( even a "low good") polish as compared to an EX with the naked eye.

Does anyone have photos that show actual stones, and why they were downgraded from EX polish grade?

How about photos showing symmetry downgrades?

 

[Rockdiamond]

HI Storm,
Sorry, I answered while you were posting.
I was going to ask specifically what type pf defects you saw, and on what part of the diamond they were located?

I have no doubt you know how to look at a diamond, I just want to know what you saw specifically.

 

[Garry H (Cut Nut)]

David why call the topic for this thread one thing when clearly you meant “GOOD finish grades are indistinguishable from EX”.

In this case we would expect you to provide case studies or some sort of teeth…not ask for “personal experiences” and disregard them all in favor of your own agenda (the topic which is not really the topic).

Now it is a good topic, and a worthwhile one, because clearly as Dave and others have pointed out, there are many reasons and ranges that lead to a diamond being graded as good symmetry. Consumers could many times be just as happy with a diamond that had ''Good'' sym, and that''s OK (I have seen and sold a GIA Good H&A''s).

But there are plenty of examples where consumers should beware of diamonds with Good symmetry, especially as Storm mentions in the case of fancies and step cuts especially. In such case one might wonder if you yourself have some other motive?

BTW Sergey also mentions frequently that one reason he suspects H&A''s are brighter than many other diamonds is that the polish is usually well done - but in the same instance, one polish line on a minor facet, vs overall polish quality is a totally different kettle of fish.

 

[Rockdiamond]

Thanks for participating Garry. If we could keep it friendly it might be informative.
I have no ulterior motives, other than to further the conversation.
I am glad to have the conversation, and my title is sincere.
I promise, I'm not trying to be confrontational.

In terms of step cuts, and symmetry- I agreed with Storm already- In my experience there are some very easy to see examples of why a stone only got good symmetry in a step cut- without a loupe.
However I have not found the same thing with polish. Either in rounds or fancy shapes. Check that- As John pointed out, girdle irregularities might have caused the downgrade- and that is eye visible- although it may have no negative impact on the overall appearance ( but of course that one might be very bad news as well)
I know I've seen some barker diamonds that were EX/EX , and some lovely G/G's
I am really interested in what people have actually seen. I'd really like to know what Storm has seen,
If there's something to see that I am missing, I'd honestly like to know about it.

How about other specific defects in polish visible to the eye- even better, photographically.

 

[glitterata]

Can some of you experts explain what different degrees of polish look like?

I sometimes see what I think might be less-than-wonderful polish on my OEC when a facet is showing fire. The rainbows are sort of unevenly striped, if that makes sense. Does that sound like a polish thing? I kind of like it, actually.

 

[strmrdr]

Date: 7/6/2009 10:23:24 PM
Author: glitterata
Can some of you experts explain what different degrees of polish look like?


I sometimes see what I think might be less-than-wonderful polish on my OEC when a facet is showing fire. The rainbows are sort of unevenly striped, if that makes sense. Does that sound like a polish thing? I kind of like it, actually.

If we are thinking about the same thing it is more of a virtual facet thing.
Direct lighting that produces strong fire would be bright enough to overpower any polish defects.
On the other hand the large open Vfs would be more likely to make it visible in other lighting if it had a polish issue.
That is assuming the diamond is clean.

 

[Garry H (Cut Nut)]

Date: 7/6/2009 9:34:58 PM
Author: Garry H (Cut Nut)
David why call the topic for this thread one thing when clearly you meant “GOOD finish grades are indistinguishable from EX”.

In this case we would expect you to provide case studies or some sort of teeth…not ask for “personal experiences” and disregard them all in favor of your own agenda (the topic which is not really the topic).

Now it is a good topic, and a worthwhile one, because clearly as Dave and others have pointed out, there are many reasons and ranges that lead to a diamond being graded as good symmetry. Consumers could many times be just as happy with a diamond that had ''Good'' sym, and that''s OK (I have seen and sold a GIA Good H&A''s).

But there are plenty of examples where consumers should beware of diamonds with Good symmetry, especially as Storm mentions in the case of fancies and step cuts especially. In such case one might wonder if you yourself have some other motive?

BTW Sergey also mentions frequently that one reason he suspects H&A''s are brighter than many other diamonds is that the polish is usually well done - but in the same instance, one polish line on a minor facet, vs overall polish quality is a totally different kettle of fish.

correction - the flatness is better

 

[oldminer]

Rockdiamond, you need to read what I wrote rather than re-intpret it. I said telling the bordlerine differences between fair to good with the naked eye would not be anything we could do any better than discerning the borderline differences between any of the other grades with the naked eye. I didn''t say you can''t see "fair" pol or symmetry issues with the naked eye. You generally can see what makes a diamond only "fair", of course, who is looking at them?

 

[Rockdiamond]

Hi All,
Oldminer, my name, like yours, is David.
Please call me David.
I don't know how anyone could read words, and not interpret them- but I apologize if I mistook your meaning.
I'm saying that it might be possible to see the reason a stone got downgraded to "Fair" polish with the naked eye due to the fact the reasons would be larger, or more important.

I'm also saying that it's impossible to see individual facets- and defects on individual facets- naked eye. Generally a on a stone graded "good" polish by GIA- even a low good, the "defect" is so small, it is only large enough to affect one facet ( not the table)

Your statement: I believe than many of us could tell the difference from a low good to a very good or excellent grade stone with the naked eye and that few of us could tell good/very good borderline stones from one another.
If it's true that "many of us" can see the difference between a low good, and a VG or EX, we'd need to see specific facets. I still don't feel that's possible.
I can't site a study, but this is a conversation.
I've asked for personal experiences, because that's a valid method of determining what people have seen.
For example- if the defect that caused GIA to downgrade to "good" is eye visible, we should certainly be able to see such a defect in photos- such as how we can see imperfections in hi res photos.

I've asked Storm for specific examples as opposed to "Yes I've seen that" as it might be possible that the reasons Storm may have thought the polish was downgraded may not have been what he saw.
In my experience, the only real way to tell if you are seeing the actual reason would be to speak to the GIA grader, and get a plot showing the reasons.

Here's a quote from John
Polish depends on how much, where, what lighting and what scrutiny. Even the GIA lab manual states polish other than EX "might affect luster seen by unaided eye." If your question was the difference between VG and EX it would be easy for me to answer based on personal experience, as I don't believe I'm capable of telling that difference with the naked eye. Maybe not G either (?) but that brings me back to the beginning of the paragraph.


As I read this, John is saying he doubts he'd be able to spot the difference naked eye.
How about you Oldminer- can you see individual facet defects naked eye?

Let me give an analogy :
A shopper is looking at two cars. A red Dodge Charger with the V8 Hemi motor, an a blue Dodge Charger with the V6 ( less powerful ) motor.

They immediately notice the red car is faster. Then, they decide that red cars are faster than blue ones.


My own personal experience is that it's fairly common for shoppers to confuse the "Polish/Symmetry" ratings with cut quality in general.


glitterata- thank you for participating, and your question is a great one.
From what you describe, to me, no , it does not sound as though there's a polish problem causing what you see.

The other part of your post- where you ask experts to describe what different degrees of polish look like is exactly on point.
A small nick, or defect in polish on your stone ( small enough to garner a GIA Good" polish grade) would not cause "fire" or any visible appearance issues. That's my point.

 

[John P]

Date: 7/7/2009 2:54:35 PM
Author: Rockdiamond

Here's a quote from John

Polish depends on how much, where, what lighting and what scrutiny. Even the GIA lab manual states polish other than EX 'might affect luster seen by unaided eye.' If your question was the difference between VG and EX it would be easy for me to answer based on personal experience, as I don't believe I'm capable of telling that difference with the naked eye. Maybe not G either (?) but that brings me back to the beginning of the paragraph.

As I read this, John is saying he doubts he'd be able to spot the difference naked eye.

It depends. I purposely used "maybe" and "(?)" for G, since it spans a broad range and there have been cases in my studies where it was possible.

Next I gave examples on request...

Date: 7/6/2009 7:16:23 PM
Author: John Pollard

Regarding the GIA manual's statement about 'might affect luster'- have you ever heard of a person being able to spot the difference naked eye- under any lighting?

Surface graining - see Strm's post. In the same way, when polish lines are heavy enough to be 'drag lines' they can show in certain lighting. Or if you have a nick that's more like a chip an observer can use reflected light to spot it the same way a clarity grader would. Like I said above, it depends on how much, where, what lighting and what scrutiny.

Next I read and applauded Oldminer's overview, which was better-stated than mine...

Date: 7/6/2009 7:54:19 PM
Author: John Pollard

Date: 7/6/2009 7:31:21 PM
Author: oldminer
Excellent is a very narrow grade. Very Good is a reasonably narrow grade, too. Good is a far broader grade.

I believe than many of us could tell the difference from a low good to a very good or excellent grade stone with the naked eye and that few of us could tell good/very good borderline stones from one another. This is because 'good' has much more range. So the end result is that sometimes we might be able to see with the naked eye that a diamond is only 'good' pol or sym and other times we might not be able to tell. I think we'd have a similar problem of where 'fair' becomes 'good', too doing it without magnification.

Good overview Dave.

That was my last post. I felt Dave summed up my experience; in a more universal way.

Sorry if I was not clear before.

 

[Rockdiamond]

Thanks John.
Rather than try to interpret, let me ask plainly.
Do you recall an instance where you ( personally) were able to see the reason for a downgrade to "good" on a stone with the naked eye prior to examining it with a loupe? If so, what type of defect, and what facet was it located on?
Your initial post seems to indicate you had not been able to see something like this naked eye.
IN an ideal situation, with a loupe, I''m sure you could, in many cases. Same lighting situation minus the loupe, I agree with the initial doubt you voiced.


You''ve agreed with the Oldminer statement that many of us can see the difference between a low good, and a VG, or EX naked eye.
That would mean we can show such deficiencies on photos.
I am very interested to see examples of the type of defects you gentlemen are talking about.

 

[strmrdr]

Date: 7/7/2009 2:54:35 PM
Author: Rockdiamond


.

In my experience, the only real way to tell if you are seeing the actual reason would be to speak to the GIA grader, and get a plot showing the reasons.

David, honestly I do not care to discuss this with you because you might twist what I say like you have already done in this thread.

Second what makes you say that I didn''t have it confirmed that it was sym/polish problems I was seeing.
It was confirmed by a GG using a microscope, I also looked at them under the scope but not until after I found them by eye.
That brings me to the second reason I don''t care to discuss it with you.
You try and insult the credibility of anyone you disagree with.

 

[Rockdiamond]

Storm- that's exactly the kind of experience I was talking about.
You were quite vague before, but I am really happy that you have such details.
There's a lot of technical terms used in conversations here.
Clarification can't be a bad thing.

When I have had to fix stones, which we have not done much, I needed the GIA diagram to see why a stone graded VG polish didn't get EX.
The cutter needed the GIA diagram to re-polish the microscopic area needing to be fixed to get it to EX/EX.
Of course, maybe he could have done it without the plot- but that would make no sense at all.

Storm, your experience can really add value to the conversation.
Do you have any specific recollections of the type of things you saw?
For example, if we were discussing imperfections- a black spot might reflect around a diamond.
I'm asking for specifics ( such as location and type of defect) so we can describe what you saw in a way people could understand - this way they would know what to look for.
Were there opaque areas?

I'd love to see photos of the type of things you saw Storm

All due repsect Storm- but I'm not trying to twist anyone's words either.
If someone makes a statement, and I understand it to mean something, how can we have a conversation if I can't respond?

 

[John P]

Date: 7/7/2009 5:35:54 PM
Author: Rockdiamond
Thanks John.
Rather than try to interpret, let me ask plainly.
Do you recall an instance where you ( personally) were able to see the reason for a downgrade to 'good' on a stone with the naked eye prior to examining it with a loupe? If so, what type of defect, and what facet was it located on?

Your initial post seems to indicate you had not been able to see something like this naked eye.
IN an ideal situation, with a loupe, I'm sure you could, in many cases. Same lighting situation minus the loupe, I agree with the initial doubt you voiced.


You've agreed with the Oldminer statement that many of us can see the difference between a low good, and a VG, or EX naked eye.
That would mean we can show such deficiencies on photos.
I am very interested to see examples of the type of defects you gentlemen are talking about.

David,

I'm trying to be clear for you, but I feel as if you're working to frame my answer one way, when it's not that simple.

I recall two naked eye instances, both in a grading workshop. The first was a cavity on a bezel facet with drag lines visible under diffused light. In the other there was a nick (or pit) on the table visible under reflected light using the flash method. I can't remember whether I used the loupe on them first or not. It was a class and we were passing many diamonds around. I didn't take photos - probably not permitted in any case - and really didn't think much of it except to make the mental notes... Frankly an SI2 diamond shown at the same workshop with internal characteristics that exactly resembled the shuttlecraft from the old Star Trek series was more memorable to me.

You posed a question at the start of the thread. Now there is a perception that you're challenging those who answered with the very experiences you sought to hear about, which would contradict the tone of your original post. Forgive my opinion if that's not the case.

In general I still think Oldminer's insight best reflected the endless scenarios that exist out there.

 

[Rockdiamond]

John, thank you so very much for the honest and forthright answer.
There's no question a conversation like this can get contentious- however it's worth taking that chance if we really want to have a fair discussion airing different viewpoints.
Many stones are knocked on PS- in the name of consumer protection.
It would be fair to say that there are knowledgeable people who believe that there are a lot of cases where stones are knocked based on too little info.
There are people saying a stone graded "good polish" by GIA is going to show eye visible defects- which in my experience is untrue.

All due respect but this is a simple question.
There's not endless scenarios on this one- either there are visible defects or not.
If they are visible, it stands to reason we should be able to see these defects in photos.

To really sort this out, details are essential.
By asking for details it might seem like I'm doubting people's responses.
However whether or not I do doubt a person;s response, the details are necessary to clarify this subject.
For example- someone says " oh I've seen that many times".
How do we know what they've seen and that there's no confusion?

Even reading your answer above- there were two instances where you recall seeing a problem with polish with your unaided eyes- and you don't recall if you used the loupe first, or afterwards.
It would make sense that if this was a common problem, you'd have seen it many times.


Garry questioned my motivation here.
Well, as a seller, my motivation - or at least part of it- is crystal clear. Same for John, and every other tradesperson here- we're here in a professional capacity- and in your case John, I'm sure part personal, as it's clear you really love what you do.
I think we share a lot of this passion in common.

There are many other people posting.
You've said you agree with Oldminer

Like both of us, David Atlas has a vested interest in proving his point.
His AGA cut charts use GIA polish and symmetry grades.
A stone of "good" polish is automatically downgraded 4 or five categories
If "good" polish commonly shows visible defects, than the charts make sense.
But what if just about every stone graded "good" polish shows absolutely NO eye visible defects?
Does it make sense to downgrade every single one- based solely on a parameter which can't be seen with the naked eye?


I know David Atlas is also a good person- and his efforts are also aimed towards helping consumers. The same can be said of most of the people posting here.
However, if the conversation is to have real value, sometimes judgements need to be questioned- and assumptions clarified..

 

[Moh 10]

Motivations?

Sellers of high quality goods explain why they are worth it.

Sellers of low quality goods must argue that good quality is not worth it.

 

[oldminer]

David (Rockdiamond), you have it wrong. In the AGA system, Polish and Symmetry have individual scores which DO NOT alter the final overall score. A sample of a result is in the photo. You can see the wording which makes it very clear. I think the kinks are pretty well ironed out in the AGA Cut Class system since it has been reviewed for a considerable number of years.

I find few diamonds which are truly well proportioned have little reason to be found or available with only "good" or worse polish or symmetry. I do not lower the overall cut grade due to polish or finish grades, but do suggest that these ought to influence price and decision making. Dealers consider these grades of some importance and consumers should be advised that these details of finish account for something even if it is only a relatively small financial consideration. On rare occasions something eye-visible in finish happens in a well proportioned diamond and we all consider this in the value and quality of that individual stone.

 

[oldminer]

Even with "poor" and the 4A warning on each component of polish and symmetry, the grade remains 1A.