Why is this stone AGS000?

[Jelly88]

Hi All - I plan on upgrading my engagement ring sometime this year and have been doing a ton of research/learning, as well as browsing available stones online. I was looking at AGS000 stones today and came across this one.

I’m curious why this one is an AGS000 when it looks like there is a ring of leakage in the middle. Is this type of leakage generally considered ok?

 

[OoohShiny]

With a 35.6 crown and a 41.1 pavilion, this must surely be right on the border of 000.

@sledge has the AGS tables to hand, I think, which might be useful!

 

[kmoro]

I believe that they grade based on the percentage of area that is red. I guess that stone managed to meet the red percentage mark. I certainly looks yucky, though.

 

[the_mother_thing]

With a 35.6 crown and a 41.1 pavilion, this must surely be right on the border of 000.

@sledge has the AGS tables to hand, I think, which might be useful!

Do you think AGS would still classify a diamond as “ideal” - even if within ‘the numbers’ - if it displayed less-than-ideal light performance with that kind of leakage? I’ll admit I’m no expert when it comes to AGS, but I assume if it’s AGS000, it’s basically hitting diamond pay-dirt in terms of cut/light performance. I wouldn’t think they’d solely ‘go by the numbers’ but I really am not up to speed on their procedures, so I don’t know.

 

[Dancing Fire]

With a 35.6 crown and a 41.1 pavilion, this must surely be right on the border of 000.

Yup, not a well cut stone. A well cut stone of this weight should be a bit over 10mm in diameter.

 

[Karl_K]

If the numbers on the raytrace software say it gets the score it gets the score unless it triggers one of the limits like spread.
Red arrows and enough green mixed with leakage and obstruction must have added up enough for it to pass.
These out there edge cases raise the possibility of not getting the score if rescanned.
I'm not a fan of them.

 

[the_mother_thing]

If the numbers on the raytrace software say it gets the score it get the score unless it triggers one of the limits like spread.
Red arrows and enough green mixed with leakage and obstruction must have added up enough for it to pass.
These out there edge cases raise the possibility of not getting the score if rescanned.
I'm not a fan of them.

I didn’t know AGS took that approach! Kinda sounds like the ‘GIA XXX’ misconception, though not exactly the same. I pretty much assumed an AGS000 would have little/no light leakage, so color me learned.

 

[Karl_K]

I didn’t know AGS took that approach! Kinda sounds like the ‘GIA XXX’ misconception, though not exactly the same. I pretty much assumed an AGS000 would have little/no light leakage, so color me learned.

The edges of ags0 are sometimes a bit ratty.

 

[sledge]

With a 35.6 crown and a 41.1 pavilion, this must surely be right on the border of 000.

@sledge has the AGS tables to hand, I think, which might be useful!

I have the original PDF version along with an Excel version I made to utilize with my custom spreadsheet. They are identical but my spreadsheet gives a smaller snapshot of the defined area.

Below are some screen caps showing how these proportions fall. I am posting two, one with a 57 table and one with a 58 table. The way the charts work are nearest whole percent increments for table values, nearest 0.5 degree increments for crown values and nearest 0.1 degrees for pavilion values.

In all cases this is NOT a stone I'd recommend for purchase. Steep crown plus steep pavilion is not a good combo. I'd also like to see a SARIN report to identify all 8 actual crown and pavilion angles.

I'd agree with Karl this is very borderline. According to the charts it should fall in excellent (1) and not ideal (0) with a possibility to slip worse.

 

[Jelly88]

Thanks so much for all the responses! I was under the impressions that AGS000 was based on having a good ASET with no significant light leakage. It’s super helpful to know that I shouldn’t be purchasing on AGS000 grading alone, and should still look at the angle combinations.

 

[Jelly88]

Another question... with these AGS000 edge cases, would I likely be able to see the light leakage in person? Or is the suggestion to avoid mainly due to being “mind clean”

 

[dumbo]

I, for one, would like to see someone do a side-by-side on a diamond such as this, vs. the typical AGS000 with minimal light leakage. Most of us that are not in the trade do not have this opportunity. I wonder if the differences are significant to the lay-person. Perhaps they are very obvious at first glance: perhaps they are very obvious when both diamonds are side by side and clean, and perhaps it is the difference between driving a Porsche Turbo and a Turbo S: 30hp and .1 sec faster 0-60 and only relevant for bragging rights.

Maybe someone can do a side-by-side and compare? I am curious as well.

As a reference, when I was shopping for an e-ring, I purchased a very nice AGS000 (but not super-ideal) and compared it against a HOF diamond of similar size. The one I purchased was much nicer than the one noted in this thread however. As I couldn't tell a difference between the HOF and the diamond I had purchased, I pocketed the extra $20k and bought my wife a gorgeous DY earring and necklace combo, along with a matching two-tone yellow gold DJ36 for our 1-year anniversary.

 

[Karl_K]

Another question... with these AGS000 edge cases, would I likely be able to see the light leakage in person? Or is the suggestion to avoid mainly due to being “mind clean”

It would be a visible difference.
Many people the only diamond(s) they spend any great amount of time with is their own and just accept what it does as what a diamond is supposed to do and would never know it is less than well cut.
Which is why the industry gets by with selling so many poorly cut stones.
How ever someone who develops an educated eye and has good eyesight could possibly pick some of them out at a glance in some lighting.
In other lighting they look closer to the same so it is very lighting dependent.
The argument going from close to super-ideal to super ideal is a much more debatable step.

 

[Texas Leaguer]

Diamond grading is generally an exercise in ranges as opposed to absolutes. Color and clarity grades are very small ranges on a continuum. So too is cut grading.

The AGS system uses actual ray tracing to score a diamond on brightness, leakage,contrast, and dispersion, so it is very objective. It is not strictly a table-based determination any more, as is the case with the GIA system. However, the categories of Ideal, Excellent, Very Good, etc are still ranges.

This diamond is clearly on the borderline of Ideal. As @sledge points out, this diamond does not get Ideal if you go by the tables. But the ray tracer can "see" that the diamond has the necessary amounts of all the required light performance factors to sneak into the Ideal category. That is, the amount of leakage, though apparent in ASET, is not quite enough for it to have suffered the amount of penalty necessary by the algorithm to receive a downgrade from Ideal.

It is important to note also that the ray tracer evaluates the diamond through a range of tilt angles, not just the face-up view we see on the ASET map printed on the report.

 

[Laila619]

It might have received AGS 000 but I'd avoid it like the plague. Not very well-cut IMO, when there are much better AGS 000/GIA 3ex stones out there.

 

[Jelly88]

@Texas Leaguer that is so interesting about the ray tracer! I did not know that it also evaluates light performance at different tilts. I had always thought that light performance was based on looking at the stone face up.

Theoretically does this mean that if a diamond has a perfect ASET face up, but the ray tracer detects enough leakage at various tilts, it may get downgraded from an AGS000 cut rating?

 

[Texas Leaguer]

@Texas Leaguer that is so interesting about the ray tracer! I did not know that it also evaluates light performance at different tilts. I had always thought that light performance was based on looking at the stone face up.

Theoretically does this mean that if a diamond has a perfect ASET face up, but the ray tracer detects enough leakage at various tilts, it may get downgraded from an AGS000 cut rating?

From a strictly light performance perspective I suppose it is theoretically possible, although in practice I don't know that I have seen it. Maybe someone else has and can post it.

Certainly a stone with a perfect ASET could get downgraded on the basis of other factors such as girdle or polish issues.

For more on the AGSL cut grading system:
https://www.whiteflash.com/about-diamonds/diamond-education/ags-cut-grading-scale.htm

 

[Jelly88]

This is so helpful - thank you!

I really wish there were more AGS stones in the market to choose from! I wonder why GIA doesn’t incorporate the ray tracer in their cut ratings if the technology is available.

 

[Texas Leaguer]

This is so helpful - thank you!

I really wish there were more AGS stones in the market to choose from! I wonder why GIA doesn’t incorporate the ray tracer in their cut ratings if the technology is available.

That's a whole other discussion!

 

[SandyinAnaheim]

That's a whole other discussion!

Break it down Bryan! Give us your thoughts please!

I imagine the expense of getting newer technology implemented is a huge factor, as there is only one AGS lab, yet numerous GIA labs around the world.

 

[Garry H (Cut Nut)]

Not impressive to someone who likes shallower diamonds.
Here is the Beta version of HCA LL - Holloway Cut Adviser Looks Like size

 

[Garry H (Cut Nut)]

In defence of AGS and this stone, I suspect it is painted resulting in an improvement in light return in this deeper combo.
That could also improve it's apparent visual size.

 

[Texas Leaguer]

Break it down Bryan! Give us your thoughts please!

I imagine the expense of getting newer technology implemented is a huge factor, as there is only one AGS lab, yet numerous GIA labs around the world.

The thing to understand is that GIA was essentially dragged into modern cut grading, even though it was obvious that cutters had been taking liberties with cut quality forever, prioritizing weight over beauty. As a result the market was full of mediocre to poorly cut diamonds, and thousands of GIA clients around the world had hundreds of millions of dollars worth of inventory in these goods.

GIA was in a difficult position. If they came out with a cut grade system, it would shine a light on this failing, and many (if not most) of their clients would be VERY upset as it could significantly devalue their inventories. But AGS saw a consumer demand for cut quality analysis and set up a laboratory to address this demand. Unlike GIA with its huge existing constituency, AGS was not constrained against developing a strict system that would make fine distinctions in cut quality. The AGS system was originally a two dimensional table-based system modeled on the proportion set made popular by Tolkowski. (*Interestingly, a few pioneering American cutters had discovered and were already cutting to these proportions twenty years earlier). The success of the AGS Ideal in the marketplace eventually (10 years later) brought GIA into the cut grading game. In the meantime AGS immersed itself to scientific research on cut quality and went all-in to develop a light performance based system that would harness available new computing intensive ray tracing.

When GIA finally launched its own grading system, it was table-based. Stone data is averaged and rounded and matched to a predefined table of grade categories in order to assign an overall cut grade. By design the categories were left quite broad in order to accommodate their large constituency of manufacturers and dealers and to avoid devaluing their vast collective inventories too severley. Even so, there was some pain felt by the trade, but they rather quickly adapted and the broad GIA EX parameters now represent a standard target for manufacturers. This has resulted in improved cut quality for rounds in the broader market. GIA has yet to add any other shapes to their cut grading service, and it is doubtful that a table-based system CAN be devised for fancy shapes because of the greater complexity and variability of these shapes and facet arrangements. This is where the AGS light performance approach really shines (no pun intended), as it is capable of being expanded to potentially any shape and facet arrangement. Already, AGSL does LP grading on princess, oval, emerald cut and certain cushions.

Even though GIA has plenty of means to develop a light performance grading system of their own, and most probably make it more sophisticated and robust, I would not expect them to roll one out any time soon. The same political constraints that caused them to delay rolling out a system for rounds, will continue to be operative. It will be up to specialty labs like AGSL to prove the concept and force GIA to respond. But GIA is such a monolith, that it seems still a long way off. You never know though – the pace of change is accelerating and information technology does tend to level playing fields.