Reading the AGA chart for Cuts

[Nicrez]

Still learning here, so please bear with me...
I have a copy of the AGA chart for Emeralds and Radiants, but there are two sets of number ranges in almost each box. Does anyone know which one is for emeralds and which is for radiants? I am looking to get good numbers for a class 2B or better cut SQUARE radiant, and lord help me, not one stone I have seen has fit the chart...Help!

 

[pricescope]

This is just the way of presenting ranges. You can see that ideal (1a) class has only one set of data. For other classes you see two ranges of numbers meaning the numbers in between these ranges belong to higher grade.

 

[Appreciative-of-expertise]

Regarding the AGA chart, I have a question regarding the specs for princess stones. Most B&M gemologists tell me that there are no specs that the industry accepts for princess stones in contrast to round brilliants. Does the industry and/or the professionals associated with this Board subscribe to those charts for fancy cuts?




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[oldminer]

Surely, there is no universal agreement about princess cut specs. However, there has been very little criticism that the AGA specs don't do a fair job so long as you ALSO examine the diamond for overall performance. While high brilliancy occurs in what I feel are well cut princess cuts, there are some odd ways to cut them where I feel the cutting is good, but the brilliancy is less than desirable...

"Cutting" encompasses a pleasing shape, durability and a good depth to width ratio. It is not simply "light performance"..

You need to consider that only a few cutters have adopted any strategy to product well cut princess diamonds. Therefore, most retailers will claim no agreement on specs and no inventory. It has some validity, but consumers will drive this issue as they increasing ask for a better cut princess. And why not? The excuse that there are not parameters is more lame every day although there is a lack of brilliancy data to make the best princess cuts buyable sight unseen.

This information is coming. It won't be years away. Take a look at www.imageminc.com and see a small taste of the future of complete diamond grading.

 

[Nicrez]

Does anyone know why almost all the Radiants I have seen so far have a table % within one range and a depth % within another? That must be pretty bad then? I have basically seen stones with flatter tables have been the kind of thin but larger in width, and the pavillions were pyramid-like. Someone said that's not that good. Is this true?

 

[oldminer]

Having one measurement in one range and another measurment in a different range is no key clue at all to cut quality. There are "rules" published for the AGA Cut Class charts and nothing addresses this very common scenario. That's how the parameters are used together to determine and overall cut grade...If they were all the same, there would be no determination required.

 

[Nicrez]

So I assume, it's best to find a stone within the ranges specified, and then that the table and depth ranges be closest within the cut ranges then? Has anyone ever even seen an IDEAL cut radiant? After searching so long, I am thinking this is a lost cause, because all the stones I have seen have different cuts, different ranges, and different %...

 

[Appreciative-of-expertise]

Nicrez, you face the same challenge that I do as it relates to princess cuts. I'm finding that it is very difficult to define specs that will provide comparable information to those who seek round brilliants. I find the AGA chart to be "possibly misleading." It is a chart that a professional designed but, to my knowledge, has not been embraced by the industry. What I believe is misleading is that AGA, which is a private company, is very close to the acronym AGS which the industry accepts. At first, when I printed off the chart, I thought it was associated with AGS. It is not. (just happens the company acronym is very similar) Oldminer did a nice job explaining above that the industry has not stepped-up to the plate yet for fancy stones; but his company did. It is not to say that his data is wrong or misleading, it's just that I haven't heard from others on this Board if they, too, embrace the numbers. My personal experience after viewing a dozen stones so far is that the numbers tell part of the story. Atleast with a princess - the eye appears to be key. Others oppinions???

 

[oldminer]

AGA is not AGS and not meant to be, either. AGS had no lab when I first publsihed and used the AGA Cut Class charts. In fact, my firm was a member of the AGS and I was a Certified Gemologist for 25 years at the time I resigned from AGS rather than have them dictate that I could not use my AGS titles on appraisal reports because my firm was a supplier member rather than a retail member. this was all brought about by the decision AGS took to offer their own AGSL services to the trade. In my mind, it was a direct blow to my own efforts to bring diamond cut grading to the trade and the public. My firm was paying $1700 per year in dues to AGS and it seemed ridiculous to send that sort of money to an organization that was going to compete with my own business and that was forbidding the use of my AGS credentials on lab reports.

The reason I used AGA instead of many other choices was only partially alphabetical preference. It was a good acronym, available for use and I knew it would occur before AGS in an alphabetical listing, too.... Yes, being a little smart is part of what it takes. No point in going down the scale to C or M or Z when there was an A that would do.

I always tell people the eyes are key to selecting a stone, but you can avoid bad stones with use of the AGA Cut Class charts. You will get a really good stone if you use the chart and carefully select the stone with your eyes, too.

Lastly, I believe the AGS Lab is for profit, just like AGA is. There were investors who sponsored the AGS Lab. If they are now out of the picture it might be non-profit now, but it was started to make money and I am sure it is now making money...big time. I wish them well as they do a superb job. AGSL has looked over the AGA charts and may well use them, all or in-part, in the coming years. I have given them blanket permission to do with them as they wish. There is more to being in business than money. I hope to contribute to knowledge, not just make a buck.

 

[Nicrez]

Very impressive to find a person who wants to impart knowledge in such an industry that favors an uniformed consumer. I have learned a lot from PS, and from the chart, I hope to get some help in findng that great cut stone. Again, still haven't found any stone within the same cut ranges, but I am hopeful... Thaks for your help with the chart oldminer, and your advice here is very appreciated. AGS IS for profit, from what everyone has been saying, but sadly, they are the only people who give grading reports with cuts and angles, unlike GIA. I can't wait to have GIA extend their reports to include cut, which is ESSENTIAL to buying a good fancy shaped diamond! Also, any ideas on how to best test a stone before buying to ensure it's a good cut (after the table?)

 

[oldminer]

Get a Sarin or Ogi report with the GIA report. We do these for dealers for a $10 fee and they can be obtained nearly anywhere... Glad to do this for anyone who wants it.

We also do full diamond grading reports that do include all the cut grading data. Most of these are done for relatively local retailers and consumers around the Philadelphia region, but we have done hundreds of reports for Internet consumers, too.

There is no good reason to think you must buy blindly. The information is there for the taking, but you do need to pursue it.

 

[Appreciative-of-expertise]

Dave, from what I have read on PS, your reputation is stellar. I, like the person who started this thread, compliment you on taking the initiative to "push" the industry and its big giants. You are so right! It is difficult for us average consumers to deduce what is reasonable for the money we are spending and, what in fact do we get for our hard earned dollars. The reason I question your chart guidelines is I've recently reviewed a princess that would rank in your top tier. To my "ave joe" eye, it had less fire and scintilation then another that i viewed that would rank much lower on your chart. Both were GIA, F/VS1. Will your Idealscope support the classifications in your chart? If I would have relied solely on your chart, my experience tells me I may not be getting from a vendor what I seek or, worse yet, I may not know that there may be possibly better looking stones available. I believe that your chart should have a disclaimer that qualifies that this is YOUR chart and not associated with GIA or AGS. Doesn't mean that it is not an exceptional "tool" but it takes away surprises like I got when I referenced it to others and better informs us that it is just that, another tool to assist in making a good decision.




I would be interested in hearing others oppinions, such as Jonathon from GOG, on this topic.

 

[oldminer]

There is no doubt that some lower graded stones perform admirably. Some will be better looking by being more brilliant or more scintillating although they have some sort of cutting deficiency. There is no easy, one step solution to this, yet... There will be, but not yet.

Meanwhile, "the eyes have it" when it comes to the final choice. Very few princess or radiant cut diamonds exist with class 1 or class 2 AGA Cut Grades. Many with class 3 grades look excellent and are the ones commonly purchased. That's okay with me, but I expect the cutting industry will be changing as more knowledge is accumulated.

We'd all like to see the various respected vendors respond here. I know that most will say that the industry presently is without meaningful standards or that paremters are not the way to select a stone. I always stress that you need your eyes for the final choice, but that when standards fully exist, they will include parameters that make the stones durable, not overly deep, and pretty in their outline as well as highly brilliant for the best grades.....

 

[Appreciative-of-expertise]

Dave,




per my earlier question, will the IDEALSCOPE results support your AGA chart?

 

[oldminer]

The Ideal-Scope is optically based and proves that brilliancy is the result of reduced light leakange and high reflection. It is much like a manual ISEE2 or a BriilianceScope, but without the electronics. Just as selecting a diamond with your eye for brilliancy, the Ideal-Scope assists a consumer or dealer to understand a diamond is highly reflective. Diamonds that are highly reflective and well cut are certainly found in the AGA system in the 1A and 1B grades. There are some highly reflective stones, ones that score well with the Ideal-Scope that are going to be in the cut class 2 range in rounds and possible in the 3 class range in a few fancy shapes, BUT diamonds in the 3A and lower cut grades have definite cut problems that may not include poor brilliancy.

In essence, the IS, BS or ISEE2, looks only for light return. The AGA Cut Classes only look at shaping, durability, and apparent size. When COMBINED, you have a very complete answer which means a lot in selecting a diamond. Light return alone is not a final solution. AGA alone is not a final solution, either. Together, you have a great result. I do look forward to the automation of this entire, dual process in the months ahead. It certainly can be accomplished with some new computerization and tools.

 

[Nicrez]

In all your experience, David, have you ever seen a Square radiant that fell within the AGA IDEAL cut standards at over 1.5 carats? I honestly don't believe anyone can cut a stone this well in this shape. If they have, I am sure not getting to see it! I have left my specs with at least 20+ diamond dealers in the Diamond District in NYC, and only one has brought me in to see anything. Am I too specific, too knowledgable (that's sad, because i am nowhere near enough!) or is my stone really NOT out there?

Jewelers I have spoken to said that the syndicate is holding onto the good stones and a large majority of the stones, and that's why they seem to be having trouble finding this....has anyone heard this rumor?

 

[Appreciative-of-expertise]

Dave, I continue to either be confused or debate your response regarding your company's AGA chart on Fancy stones. I believe that this is also what is causing this thread's original author some anxiety, as it did me.




Unless I have missed the boat along my journey since coming aboard PS, it has been my understanding that a diamond's life (brilliance, fire, scintilation) is directly associated with light leakage and refraction within the stone. It has also been my understanding that light leakage/refraction performance is directly associated with the "cut" of a stone. Therefore, I have drawn the conclusion that cut, diamond's life and light leakage all have correlation to each other. It has also been my understanding that when one talks about an "Ideal Cut" they expect all of the above. Please correct me if I am mistaken, but if not, then how could you say above that "The AGA Cut Classes only look at shaping, durability, and apparent size. " and have cuts defined as "Ideal" in your AGA chart that don't take all variables into consideration? Would other professionals agree that an Ideal cut is the same as you have defined it?




I have also used your IdealScope and reviewed two stones side by side, one that would fall within your "Ideal" category, the other "Class 2B." The latter had better views through the scope then what your AGA defined as "IDEAL." This does not feel good as a consumer!




I spent a lot of time, searching for the right stone based on your chart and not understanding why so many PS and B&M people kept discounting the specs on the AGA guide. I commend you for trying to make this more of a science with fancy's then is available and only suggest that you qualify on your charts that this is not sanctioned by the GIA or AGS but should be considered a tool to assist people in their purchase ,along with the fact that it does not take into consideration the diamond's brilliance, fire and scintilation when defining "Ideal."




If I have missed the boat....then my sincere apology for venting this frustration online.


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This is why I believe that unless I am wrong, AGA has a responsibility to the consumer to educate them to this on that chart. Not leave it to the average joe to discern it for themselves.

 

[fuffi]

Nicrez-

Henry Grossbard, the developer of the radiant cut is still cutting them to his original specifications. I can only assume this would be as good a radiant as one can get. I know they are available through Washington Diamond. I'm not sure where else you might find them, but it may be worth looking into.

http://www.bigdiamond.com/pages/rad-why.asp

 

[Nicrez]

Fuffi, I have tried almost every place that sells the generic, and they just don't cut them right. Thanks soooo much!