AGA revised Cut Class grades now live

[oldminer]

With some excellent input from Jonathan at Good Old Gold, I have revised all four of the AGA Cut Class grade charts and the automatic cut grading on the gemappraisers.com website.

While the changes are not large ones, they will improve their value in terms of judging diamonds before you see them. You still need to look at diamonds for brilliancy and for many reasons that these charts just don''t cover, but they are very helpful in the screening process. A lot of expertise has refined them over the years and I am glad to be able to let people work with them at no cost.

 

[Jaded Gem]

Thanks Dave for letting everybody know about the updates to your Atlas' Cut Grading site. I have used it many times before, and I found it to be very useful. It's always great to have the experts share their knowledge with people like myself who are less knowledgeable. Thanks.

 

[Nicrez]

David, as always so thankful and so impressed by your level of professionalism and pride towards your profession! What an asset to the Diamond community! In other words THANKS! YOU ROCK!

 

[Stephan]

34.0°-34.7° is a nice change, in the past 34.3°-34.7° was a little to severe.

 

[Mara]

Thanks for the update, Dave! Will have to re-run my stones through again.

 

[Giangi]

Smart move, Dave. The new parameters are very helpful and a little less tight -- allowing people to get stones that in the past weren't considered because they weren't the top of the top, if you know what I mean.

Well done job!

 

[oldminer]

It is a two edged sword. I set high standards and they were so tough that they were diminished in value to people. Now, with just a little tweaking, I believe there will be some better use for the process. I don't think I have gone too far in the loose direction, but have made what I'd consider small adjustments that just make them better.

 

[valeria101]

Is there any way at present for buyers to get DiamCalc reports on their fancy stones before buying? With Sarin reports in hand, it is still not straightforward to make much use of the numbers if one wants to hunt down brilliant stones.

I would deduce that the current set of numbers in the AGA charts would not make a complete set of parameters to plug into a such a simulation, if one chooses to (same as for the HCA bit, with things made worse by the extra degree of freedom for fancies' proportions)... IS there any relation between the AGA and some method of determining the optical properties possible for each cut class ? For example, is high light return achievable within each AGA cut class, for certain cut details aside those expressly mentioned but he charts?

Of course, this is just my curiosity at work... hoping not to go wrong!

 

[oldminer]

High light return is possible in many of the AGA Cut Class levels. These charts pertain to quality of cut and do not predict brilliancy alone. The reason is that a given diamond can be cut "right" or have many faults which pertain to durability or lack of visible "size" for their weight. They can be misshaped in some respect which will be adverse to the end user although they might be unaware of the cut problem unless they looked into what defines a finely cut diamond. The charts help people to judge cutting without an inherent understanding or knowledge of the subject. There is no shortcut to total experience and knowledge, but these are useful parameters.

Some components of what makes a diamond "brilliant" are not included in charts such as these because of the number and variety of the variables which have an effect on visual appearance and light. Devices to measure light or programs which calculate light are required for this. However, I feel one would not willingly select a poorly fashioned diamond only because it had fine light return unless their budget called for it, or unless they were seeking out some unusual combination for their own private reason. There will not be a large market for odd-ball, but brilliant diamonds. This is a certainty. Maybe a few folks will want some strange configuration, but this will never be commonplace.

The AGA parameters pretty much define the norms of shape and cutting for the general public and dealers. They tell you the "sweet spot" of cut and shape. Stones which diverge below AGA 2B in grade will have some sort of "problem" that you may not understand, but a diamond dealer would. Would they tell you about such a problem? I think the answer is clear that they would say very little if no one asked. Sadly, little is told the retail customer even when they do ask by many sellers. This happens from lack of knowledge and/or unwillingness to be open about the reasons why a certain diamond is priced differently than a better stone. It isn't an evil thing, but just the way many material things are typically sold. Buyer beware is a good phrase to keep in mind.

Buy your precious things from folks who earn your trust and confidence. There are many super vendors out there, but it is up to you to find them. You are already in one of the right places to make that happen.

 

[nelmr]

I was just wondering why the girdle thichness was changed to verythin in a class 1A instead of the orginal thin to medium, medium to thick. I'm referring to princess cuts. Thanks

 

[oldminer]

We see many AGS 0 cut diamonds with thin girdles and felt that they know what they are doing in this regard. It is a small attampt to bring my somewhat arbitrary grading into a reasonable alignment with industry practices. I may feel that a medium giurlde is "perfection", but we see no real problem with a thin girdle other than in past tradition it was not as highly regarded. In today's world, such is not the case any longer. Thin is in, one might say.

I hope that explains it...