AGS less strict on colour?

[max1111]

Just wanted to share the gradings given on a few super ideal stones I've been offered. Obviously it's a very small sample size but has given me pause for thought.


1.24ct, Round brilliant Ideal cut diamond.
GIA- I in colour VS1 in clarity
AGS- H in colour VS1 in clarity
Gcal- H in colour VS1 in clarity


1.07ct, Round brilliant Ideal cut diamond.
GIA- G in colour VVS2 in clarity
AGS- F in colour VS1 in clarity
Gcal- G in colour VS1 in clarity


1.19ct Round brilliant Ideal cut diamond
GIA- E in colour VS2 in clarity
AGS- E in colour VS2 in clarity
Gcal- E in colour VS2 in clarity

 

[yssie]

Wolf CBI triple-certed their offerings (GIA, AGS, and GCAL). Back when they first launched a PSer went through their entire online inventory and tallied up colour grades for all stones per GIA vs. AGS.

It was the first time such a large and objective inventory had been made available to the public to do such a breakdown with. If you ignore the surrounding conversation and read through posts that focus on the inventory comparison, you may find the result interesting.

The New HPD website is live now!

Check it out: www.hpdiamonds.com many new images....! Very exciting!

www.pricescope.com

 

[DejaWiz]

This is completely dependent on personal preference, but one color grade difference usually isn't going to be obvious and apparent.
One color grade difference between reputable labs can (and does) happen, but probably not to a huge extent...the important thing to keep in mind is that grading is based on human opinion and offers no guarantee of accuracy (it's even in the fine print of each and every grading report), and even the same human working in a controlled environment lab can provide a different opinion on things like color and clarity on different days of the work week. If the grader assigns a color grade, another (senior ranking) grader/supervisor must concur before the color grade is signed, sealed, and delivered.
There's a widely accepted method of guidelines to it, but not a sure-fire definitive fool-proof industry standard process.
That being said, I would certainly place a bit more trust in GIA color grading for anything F or lower. AGS, GCAL, and IGI next. All other labs last. This, for me, is applicable to labs widely utilized for diamonds sold in the US/NA market, and I do realize there are some fantastic trustworthy labs in other parts of the world whose grading reports we don't get to experience much, if at all.

 

[max1111]

If you ignore the surrounding conversation and read through posts that focus on the inventory comparison, you may find the result interesting.

The New HPD website is live now!

Check it out: www.hpdiamonds.com many new images....! Very exciting!

www.pricescope.com

Very interesting and also a bit worrying given you could easily end up paying for a higher colour grade with AGS than is widely accepted by the market GIA.

I ran my own numbers using the same site and it gave me -

60% AGS+GIA same grade

40% AGS graded higher

 

[max1111]

This is completely dependent on personal preference, but one color grade difference usually isn't going to be obvious and apparent.
One color grade difference between reputable labs can (and does) happen, but probably not to a huge extent...the important thing to keep in mind is that grading is based on human opinion and offers no guarantee of accuracy (it's even in the fine print of each and every grading report), and even the same human working in a controlled environment lab can provide a different opinion on things like color and clarity on different days of the work week.

I found the grades very easy to differentiate in person! No problem putting stones order.

I quickly tallied up all the stones on the old HPD site and AGS was a colour grade higher 40% of the time. 60% of the time it was the same. AGS was lower 0% of the time.

That sounds like a bit more than an anomaly to me! If it was just down to human error you would expect an equal spread of results right?

 

[MamaBee]

I had an AGS certified diamond that was graded by them as being a G…Fifteen years later I sold it. The buyer sent it in for a GIA cert. It came back an F. This is just one example..

 

[DejaWiz]

I found the grades very easy to differentiate in person! No problem putting stones order.

I quickly tallied up all the stones on the old HPD site and AGS was a colour grade higher 40% of the time. 60% of the time it was the same. AGS was lower 0% of the time.

That sounds like a bit more than an anomaly to me! If it was just down to human error you would expect an equal spread of results right?

You have a tremendous level of color sensitivity (I'm sensitive to 2 grades, which is probably considered somewhat high).
Definitely shop off of the GIA color grade!

 

[DejaWiz]

I had an AGS certified diamond that was graded by them as being a G…Fifteen years later I sold it. The buyer sent it in for a GIA cert. It came back an F. This is just one example..

So AGS was more strict in this instance.
I remember seeing a few more examples of that happening from the WolfCBI site a while back.

 

[max1111]

You have a tremendous level of color sensitivity (I'm sensitive to 2 grades, which is probably considered somewhat high).
Definitely shop off of the GIA color grade!

Who knows maybe I was lucky

GHI , big difference in colour imo

 

[max1111]

I had an AGS certified diamond that was graded by them as being a G…Fifteen years later I sold it. The buyer sent it in for a GIA cert. It came back an F. This is just one example..

15yr difference in grading standards could be at play here.. Clarity grades have definitely slipped from what I've seen, maybe colour has too?

Looking at prices there is a big difference between colour grades particularly in the G-J range

 

[MamaBee]

15yr difference in grading standards could be at play here.. Clarity grades have definitely slipped from what I've seen, maybe colour has too?

Looking at prices there is a big difference between colour grades particularly in the G-J range

Every appraiser that has seen the diamond over that time said they felt it was an F..not even close to a G. Maybe the person at AGS was off that day. Who knows.

 

[Rockdiamond]

Every appraiser that has seen the diamond over that time said they felt it was an F..not even close to a G.

Many feel that color grading at GIA is all being done by machine at this point...very likely AGSL as well.
Speaking as a human who was trained to grade diamond color....
The difference between F and G is very slight. A machine might consistently re-grade the same.....but humans will vary in re-grading.
Depends on the time of day, the lighting...so much.
Part of the argument that GIA is using machines to color grade is how consistency has improved....it wasn't like this 20 years ago

My point is that even though @MamaBee's appraisers were totally consistent, that is by no means a rule in the real world.

And to the specific point of this diamond- I believe the time involved is relevant here- for the reasons I've stated....

 

[daisygrl]

This is completely dependent on personal preference, but one color grade difference usually isn't going to be obvious and apparent.
One color grade difference between reputable labs can (and does) happen, but probably not to a huge extent...the important thing to keep in mind is that grading is based on human opinion and offers no guarantee of accuracy (it's even in the fine print of each and every grading report), and even the same human working in a controlled environment lab can provide a different opinion on things like color and clarity on different days of the work week. If the grader assigns a color grade, another (senior ranking) grader/supervisor must concur before the color grade is signed, sealed, and delivered.
There's a widely accepted method of guidelines to it, but not a sure-fire definitive fool-proof industry standard process.
That being said, I would certainly place a bit more trust in GIA color grading for anything F or lower. AGS, GCAL, and IGI next. All other labs last. This, for me, is applicable to labs widely utilized for diamonds sold in the US/NA market, and I do realize there are some fantastic trustworthy labs in other parts of the world whose grading reports we don't get to experience much, if at all.

It is not always apparent but that also depends on the size of the stone. Going up one color grade in the size I have would cost me additional $10,000 or so. So it can be upsetting if you are buying a AGS F and GIA grades it to be a G.

 

[DejaWiz]

It is not always apparent but that also depends on the size of the stone. Going up one color grade in the size I have would cost me additional $10,000 or so. So it can be upsetting if you are buying a AGS F and GIA grades it to be a G.

That is absolutely a fair statement.
I don't think AGS is being intentionally deceiving, unlike some other grading labs notorious for doing so in order to wrongfully drive up the price on inferior diamonds, but your point is absolutely valid and that should always be a consideration, no matter the carat size, because it DOES impact pricing to the buyer.

 

[max1111]

It is not always apparent but that also depends on the size of the stone. Going up one color grade in the size I have would cost me additional $10,000 or so. So it can be upsetting if you are buying a AGS F and GIA grades it to be a G.

Yeah the issue as I see it is you could easily be overpaying by 20-25% in certain colour grades.

Assuming the HPD numbers bare out across all AGS stones (I don't see why they wouldn't) then 40% of AGS only stones are grossly overpriced.

 

[Texas Leaguer]

This topic comes up on this forum with fair regularity. No doubt because many people here gravitate to AGSL reports based on the superiority of their light performance cut grading, but are also aware of the overall reputation of GIA as the most trusted source of diamond grading worldwide. To a large extent, the perception is that GIA is the ultimate arbiter. Even though GIA themselves has had problems with grading consistency over the years managing their growth to over a dozen grading facilities spread around the globe.

With regard to color and clarity grades, there is a factor of “dog bites man is expected. Man bites dog makes news”! When consumers get an upgrade from GIA, they consider it good fortune and rarely complain. When the grade is higher at another lab, it is because that lab made a mistake or grades “softer”.

There are a number of other things to keep in mind when trying to evaluate the grading accuracy of different labs. First of course is sample size. The original post has three diamonds. One of which the labs all graded the same, and one of which GIA graded clarity higher (is GIA softer on clarity?). Interestingly, and to the point of the paragraph above, nobody has mentioned that data point.

The introduction of a small inventory of diamonds with multiple certs makes for a more intriguing survey, but still a very small sample size compared to all the diamonds that are submitted to these labs. In addition, this is the carefully curated inventory of a single dealer - not the general production of a large manufacturer. There are vetting procedures in this curation that can lead to differentials that may seem exaggerated to someone assuming this group of stones is representative of all diamonds.

There is a known and accepted 1 grade +/- tolerance in the diamond trade between top tier labs. That is because color and clarity grades are very small ranges on a continuum. Therefore, a grade can literally be strattling two grades and may fall on either side, no matter who is doing the grading.

It should also be noted that GIA and AGS are sister organizations. AGS graders are GIA trained and GIA vetted color masters are used in their color grading. Consistency with GIA is a priority for AGS. (which can present challenges as GIA evolves and grows.)

Some years ago another survey (graph below) was conducted based on all the diamonds listed on a global database, and looking at the pricing of equivalent grade diamonds from various labs. This too, is not a scientific study, but is a telling snapshot. Diamonds with grading reports issued by labs considered to be ‘softer’ would be expected to be discounted relative to GIA, and they are. Note that AGS reports actually brought a premium over GIA in the market. Would this be the case if the overall grading was “softer”?

 

[yssie]

Note that AGS reports actually brought a premium over GIA in the market. Would this be the case if the overall grading was “softer”?

Yes

Because this is primarily due to the fact that the people buying stones with AGS certs are a self-selecting niche of customers who are willing to pay more for AGS’ cut grade, and who actually prioritize that cut grade over all else - including GIA equivalence in colour/clarity. It’s a statement on differentiation in market/audience priorities, not proof of AGS reputation in terms of comparison against GIA’s colour/clarity grading norms. Industry sentiment outside PS is that AGS is regularly softer on colour.

GIA is the global standard for all major sales and auction venues. For someone who wants to know what the GIA grade would be - the only way to know for sure is to send that stone to GIA. I’m one of those people (I'm sure you're shocked ) so I’ve had all my major stones dual certed.

For anyone reading who doesn't know me - WF is my go-to diamond vendor and ACAs are my go-to flavour of precision-cut H&A RB. I also value precision in cutting more highly than colour, once a personal baseline threshold for both has been met

Phone, edits*

 

[max1111]

There are a number of other things to keep in mind when trying to evaluate the grading accuracy of different labs. First of course is sample size. The original post has three diamonds. One of which the labs all graded the same, and one of which GIA graded clarity higher (is GIA softer on clarity?). Interestingly, and to the point of the paragraph above, nobody has mentioned that data point.

Funnily enough I went back through the HPD looking at clarity only.

GIA graded higher for clarity than AGS in 15% of stones. 85% were graded the same and on 0 occasions they graded lower.

Again the rumour does bare out in these numbers at least.

The introduction of a small inventory of diamonds with multiple certs makes for a more intriguing survey, but still a very small sample size compared to all the diamonds that are submitted to these labs. In addition, this is the carefully curated inventory of a single dealer - not the general production of a large manufacturer. There are vetting procedures in this curation that can lead to differentials that may seem exaggerated to someone assuming this group of stones is representative of all diamonds.

What vetting procedure would you guess could give rise to the size anomaly?

I'm open to other explanations but until then the only data point that is publicly available is the HPD site. Of 66 stones - 40 had the same colour grade, 26 were graded higher than GIA. 0 were graded lower.

Again the rumours and anecdotes do seem to have their roots in fact.

There is a known and accepted 1 grade +/- tolerance in the diamond trade between top tier labs. That is because color and clarity grades are very small ranges on a continuum. Therefore, a grade can literally be strattling two grades and may fall on either side, no matter who is doing the grading.

Accepted but the one bit of data available seems to back up all the anecdotal evidence on this site at least..

This too, is not a scientific study, but is a telling snapshot. Diamonds with grading reports issued by labs considered to be ‘softer’ would be expected to be discounted relative to GIA, and they are. Note that AGS reports actually brought a premium over GIA in the market. Would this be the case if the overall grading was “softer”?

It seems fairly obvious to me that producers will send to the lab that will give the best result financially. I'm sure they have an idea of the grade before it gets sent off if they are producing thousands of stones. I'd be more surprised if they didn't have qualified graders in house. *tin foil hat off*

On James Allen about 85% of AGS stones are ideal cut. If I was a betting man I would guess a big percentage of these are stones that have already or will miss the next colour grade with GIA. I'm happy to be proven wrong here but there is too much pointing in the same direction..

For example a - G VS1 is worth a lot more than an H VVS2 regardless of lab.

 

[Texas Leaguer]

@yssie ,
You have a good point about bias toward top cut quality being reflected in the Rapnet survey. How much is the price being impacted? 6%? More or less than 6%?
I prefaced my statement by saying that this too, is not a scientific analysis. It's very open to interpretation and speculation, but I think it signals something meaningful.

I also agree that if you want or need an additional lab report on a diamond, you can always order one. But it's important to know what you wish to accomplish and what you are going to do with the results, especially if there is a divergence in some aspect of the grading that is within normal tolerance.

I disagree that this statement is of value to consumers: "Industry sentiment outside PS is that AGS is regularly softer on colour." When you consider the many myths that are still propagated by the industry in areas such as fluorescence, cut quality, twinning wisps and clouds being ideal clarity characteristics because they are hard to see, etc., "industry sentiment" should be taken with a big grain of salt. Most people in the industry only know GIA, and only sell GIA. Many have a strong self-serving bias against other labs which often manifests in misinformation, even if they are not being intentionally misleading.

 

[Rockdiamond]

I disagree that this statement is of value to consumers: "Industry sentiment outside PS is that AGS is regularly softer on colour." When you consider the many myths that are still propagated by the industry in areas such as fluorescence, cut quality, twinning wisps and clouds being ideal clarity characteristics because they are hard to see, etc., "industry sentiment" should be taken with a big grain of salt. Most people in the industry only know GIA, and only sell GIA. Many have a strong self-serving bias against other labs which often manifests in misinformation, even if they are not being intentionally misleading.

Interesting discussion!
I can argue both sides of this.
The vast majority of dealers have no idea what an ASET is....much less the sort of discussions frequently occurring here on PS regarding finer aspects of cut and other things.

But who might actually read this very discussion?
Bryan referred to the statements " value to consumers"
Of course, the vast majority of consumers won't read this discussion.
So in that regard- the fact that readers of this forum are more informed than most dealers...I think it's a valid discussion and raises valid points. Statistics can be misleading- but in this case, it really does seem clear that AGSL is slightly softer on color grading, versus GIA.

 

[DejaWiz]

the fact that readers of this forum are more informed than most dealers

 

[max1111]

Industry sentiment outside PS is that AGS is regularly softer on colour.
*

The impression I get is that this sentiment is shared by the majority of prosumers on PS at least.

 

[yssie]

I also agree that if you want or need an additional lab report on a diamond, you can always order one. But it's important to know what you wish to accomplish and what you are going to do with the results, especially if there is a divergence in some aspect of the grading that is within normal tolerance.

I think for most of us in this category it’s a point of interest and nothing more. My decision to purchase wasn’t based on anything other than the report the stone came to me with, at time of sale. I’m sure I paid a premium over GIA EX/EX/EX for my AGS0 stones - I don’t know how much of a premium, but I was happy to do so.

I disagree that this statement is of value to consumers: "Industry sentiment outside PS is that AGS is regularly softer on colour." When you consider the many myths that are still propagated by the industry in areas such as fluorescence, cut quality, twinning wisps and clouds being ideal clarity characteristics because they are hard to see, etc., "industry sentiment" should be taken with a big grain of salt. Most people in the industry only know GIA, and only sell GIA. Many have a strong self-serving bias against other labs which often manifests in misinformation, even if they are not being intentionally misleading.

I understand what you’re saying, and I also understand the context in which you’re saying it - you’re a tenured industry professional who’s “been around the block” many times. However, I do want to caution that when tradepeople share sentiments like this here in good faith, consumers often boil those sentiments down to Noone outside PS can be trusted, and the natural extension of that belief is I’m learning on PS and and I’ve got the charts and pictures, therefore I know everything, and Anyone who doesn’t do things the PS way is incompetent or untrustworthy. And as *we* know - that’s very untrue.

In any case, there are many reputable vendors who aren’t on PS, and who do have experience with multiple certs, and whose experience has informed them that AGS is regularly softer on colour than GIA. This has been the predominant sentiment for years and years, but it wasn’t until Wolf CBI published their (not-insignificant) inventory (of precision-but H&A RBs) that we saw this bit of industry zeitgeist borne out. But there it was, in black and white, irrefutable.

I have never understood the argument that one letter grade is within reasonable uncertainty (outside of, say, appraising a mounted stone for insurance). When I buy a colourless or near-colourless stone my credit card isn’t charged equivalently for adjacent letter grades - I’ll pay more an F than an otherwise-identical G, I’ll pay more for a G than an otherwise-identical H. If one letter grade of uncertainty is truly reasonable then how does the trade justify pricing by specific letter in the D-J grades? Once you get into the split grades it really is a free for all so let’s just ignore those ranges. (FWIW Wolf CBI chose to price by colour and clarity per the GIA, not the AGS, citing the fact that GIA is the world-renown standard).

I’m not advising that anyone discount an AGS report or demand multiple certificates prior to purchase. AGS is an extremely reputable and respectable grading authority. But if one has a stone with an AGS report and wants to know what the global standard would say, then there’s only one way to find out, and consumers should be aware that there’s a very real possibility that the GIA grade will be lower.

 

[Karl_K]

This is just my opinion based on my experience:
We went with AGS with Octavia because GIA was all over the place on color grading on them.
Large differences on rechecks and 2 similar stones getting widely different color grades.
AGS was much more consistent on color grading of fancies at that time, with all the added GIA labs I have no doubt that is likely the case today.

With rounds over the years my opinion is that AGS is a bit soft on color grading at times. Mainly on splits where GIA goes low and AGS goes high. But then again I have no evidence on how consistent GIA is with itself as a comparison.

AGS was much stricter in the vs2,si1-2 and i1 border areas at times. In my opinion that was because GIA shifted over time. My opinion is AGS has now followed for the most part. There are areas where they still might be a little more strict but not as much as in the past.

Remember they are chasing GIA and there is going to be leads and lags. There are times when GIA is chasing its own tail on consistency with all the new locations.

That is why GIA should not be allowed to set the standards and instead there should be an international standard that all labs grade to.

 

[yssie]

That is why GIA should not be allowed to set the standards and instead there should be an international standard that all labs grade to.

Or forget colour grading altogether and just tell me the absorption wavelengths and degree of absorption at each one

 

[Karl_K]

Or forget colour grading altogether and just tell me the absorption wavelengths and degree of absorption at each one

I would enjoy that data! But that would make about 5 people that would.

 

[DejaWiz]

I would enjoy that data! But that would make about 5 people that would.

Six

 

[oncrutchesrightnow]

Six

Seven.

 

[Karl_K]

ok 1,6,7 How would you explain this to a PS newbie?

I have a very limited number of these and not in higher colors(d-z) so dont ask for an I :}
@yssie @DejaWiz @oncrutchesrightnow

 

[Karl_K]

Here is another before I hit the zzzzzzzzzzzzzzzzzzzzssssssssss