AGS announces their new AGS 0 parameters

[oldminer]

Early yesterday AGS announced their new cut grading parameters. They are eliminatng the thinnest and thickest stones, but greatly expanding, based on light performance, the scope of what will be called "ideal".


On the surface it sounds like some good changes, but I don''t think 31 degree crown angle diamond will be desireable from a durability standpoint even if they are highly brilliant and attractive. They may be super light performers, but "ideal", I don''t think so. A very well respected cutter told me that the cost range for the best to worst of the AGS 0 stones is 20% less for the poorer types all within the AGS 0 grade.

It doesn''t take a genius to know that many poorer cut AGS 0 diamonds will now be made instead of really "ideal" ones. Its the economic reality and I believe most unfortunate.

We will continue to refine and develop the AGA cut Standards with renewed vigor, as I see real problems with the AGS strategy that held so much hope. I think they have made a less than "ideal" choice. Light performance is only a portion of what makes a superb diamond. It is not the ONLY element to a diamond being at the top of the scale.

The above is my opinion, but I don''t think there is any question that "Ideal" is a superlative and should not have a wide definition that covers many non-superior stones....

 

[Garry H (Cut Nut)]

I think once you see nice symmetrical 31 crown and 41.4 pavilion diamonds Dave, you will not be unhappy.

 

[Paul-Antwerp]

Hi David,

Without data in hand, I cannot possible comment. Where and how did AGS announce these new parameters?

Like you say, this development has been long awaited, so I am very curious about the outcome.

 

[Garry H (Cut Nut)]

Paul remeber Peter Y said in Moscow that AGS 0 will go down to 30 Crown with appropriate pavilion angles.

 

[Paul-Antwerp]

I think that I do, Garry, but I also remember a maximum deviation of 1% of the diameter. So, for a 1Ct., I would assume between 6.44 and 6.56, presuming that we put 6.50 as median.

 

[oldminer]

Garry:

I don't doubt for a minute that I will think the 31 degree crown stones with proper pavilion angles will have excellent light return and sparkle. No doubt, AGS is sure enough on that and I trust that part of the science, and I respect your judgment, too. HOWEVER, I do not automatically go from high light return to "ideal cut" in one step. One MUST have durability and beauty along with an appearance that is pleasing. I am afraid durability may be an issue, but we'lll have to see. I do know that shallow crown, deep pavilion diamonds are less costly to produce, but I am afraid the value of "IDEAL" will be substantially diluted from this very commercial approach. Few cutters will cut the really top quality cuts and that's not good.

The AGS approach fits the Ideal-Scope system, so that is just fine and I know we have a vested interest in that part of judging cut, however, I do not judge overall cut quality by light performance alone. Many others do not, as well. Sure, diamond dealers love liberal grading, but when one uses a superlative, "IDEAL" the diamond should be TOP quality not just have a component of top quality..... That's what I think.

 

[diamondlil]

David,
I'm still learning here, but how does a shallow crown angle cause a durability issue?

Just curious.

Thanks,
DiamondLil

 

[elmo]

Did they make any announcement about "performance-based" grading i.e. somehow measuring "performance" or optical symmetery with a device, or is this simply a revision of their current proportions-based system?

 

[oldminer]

Diamond by its very nature has perfect cleaveage. This makes it rather liable to break although it cannot be scratched except by another diamond. Also, diamond is brittle and once the crown angle becomes too shallow for durability, at about 31/30 degrees, there is an increased in the damage potential.

Round diamonds with shallow crown heights and shallow crown angles do not look the same as tradional Ideal Tolkowsky style cuts. They may be lovely for light return, on occasion, but they will look a little unusual to trained eyes. I don't yet know how this all will work out. The public may love it, or they may feel misused. The standard has been weakened in one way while tightened in another. The jury is out.

 

[flowergurl]

Old Miner: What about a stone with 31.9 crown angle- is there a durability issue there in your opinion? I know that # is just an average of all the angles...

 

[flowergurl]

And the pav. angle is 40.8, if that makes a difference.

 

[oldminer]

I do not presently have the AGS grading manual, so I cannot answer specifics. 31.9 is well above 31, so I'd say that unless the girlde is very thin there is no durability problem.

 

[lenhejo]

Where can we view these new parameters? I searched the AGS website with no luck.

 

[Bagpuss]

What parameters would you say would make a safe ideal cut diamond?

Around these ones?

Table Diameter: 52.4 - 57.5%
Crown Angle: 33.7 - 35.8°
Pavilion Angle: 40.16 - 41.25°
Girdle Thickness: Thin, Medium, Slightly Thick
Culet Size: None, Pointed, Very Small, Small, or Medium

 

[oldminer]

A "Safe" ideal cut round diamond is AGA 1A or AGA 1B. It has always been this way and will continue to be the same. This is because nothing inherent in diamond has changed, only the system AGS intends to promulgate. They have basically adopted the AGA 1A and 1B tightness in parameters, but have extended their blessing of AGS 0 to cover highly brilliant, but somewhat slightly off-make stones in place of their previous problematic steep/deep ones. We will now have shallow crown/deep pavilion as a possible stone for AGS 0. There was no trade off necessary, but I suppose it would have looked bad if they just had used the AGA parameters. I told them they were welcome to do so. Instead they have opted for a different, again I believe, overly liberal interpretation, of what "Ideal" really means.

Diamond dealers who only want the money won't care. Diamond dealers who care about integrity to their trade are not going to be happy about the newest AGS system, but they will do what is needed to make a living. I don't blame any diamond dealers because they are now being led by the major labs like a bull with a ring in its nose. Instead of producing the best products, because they know the art of cutting, they are going to allow a different sort of leadership, one of technology, to lead in another direction.
Who knows where this will take us? I'm in for the ride.