AGS Square Princess Cut Guidlelines (Chart or Table)

[niceguymr]

Hi and thanks to everyone who contributes to this forum. I''ve learned so much about diamonds in the last week from this forum that I''ve actually amazed some jewelers.

It looks like I''ll be buying my girlfriend a Princess Cut engagement ring soon. I''ve found the AGA Charts for Ideal Cuts for Princess shaped diamonds. However, there seems to be a lot of ''noise'' circulating about the AGS guidelines, but I can''t find them anywhere. Can anyone point me in the right direction for the AGS Cut Guidlines for Square Princess Diamonds?

 

[JulieN]

http://www.infinitydiamonds.be/newsletters.php; just some reading material related to this

 

[niceguymr]

That information is ok, except I''m hoping to find some tables/charts with some cut angles, percentages, etc. Is what I''m looking for even available?

 

[Garry H (Cut Nut)]

The AGS charts are for manufacturers who have 100 time better equipment than vendors - you will find it very difficult to get the accuracy of scan info that you need to use those charts.

But the good news is that anyone who has a stone can tell you or send you a photo thru an ASET scope because that is how the charts were made (using DiamCalc).

If you can trust me - the charts will be absolutely useless to you.

 

[Garry H (Cut Nut)]

oops - forgot the pic

 

[oldminer]

The AGA Princess cut charts really don''t work well with the new AGS0 princess cut. Antwerp Paul has pointed out how diffreently these particular diamonds are fashioned. They are diffreent than typically cut princess cuts. Don''t confuse yourself with the AGA system and the new AGS0 princess......

 

[WinkHPD]

Date: 4/23/2006 7:47:14 AM
Author: oldminer
The AGA Princess cut charts really don''t work well with the new AGS0 princess cut. Antwerp Paul has pointed out how diffreently these particular diamonds are fashioned. They are diffreent than typically cut princess cuts. Don''t confuse yourself with the AGA system and the new AGS0 princess......

Dave went to great lengths to provide a guideline when none was available and it was a good guideline. AGS spent millions of dollars on research and came up with the ASET tool to use in evaluating The actual light performance within a diamond. It led to better ability to evaluate each diamond, even those shapes for which there is no formal AGS cut grading standard.

I have to admit that I do not well understand the charts, but I can pretty accurately judge any stone using an ASET tool. Unless you are a number crunching genius, or have the Octonus Diamcalc software, you will find the charts of little aid.

Wink

 

[oldminer]

With ImaGem technology, we are able to clearly define directly measured light performance of princess cut diamonds. This includes traditionally cut ones and the new AGS style ones, too. You don''t need any chart to understand simple measures of brilliancy, sparkle and intensity. I wanted to address the inadequacy of the AGA charts in my previous posting, but there is an elegant alternative now available.

 

[zhuzhu]

I think niceguymr was looking for a numbering chart that can "suggest" a high class stone using just the set of numbers Sarin provides, in the absence of other machinery reading. This maybe the chart he is looking for. http://diamonds.pricescope.com/fnc1.asp

 

[Paul-Antwerp]

Date: 4/23/2006 12:31:44 PM
Author: zhuzhu
I think niceguymr was looking for a numbering chart that can ''suggest'' a high class stone using just the set of numbers Sarin provides, in the absence of other machinery reading. This maybe the chart he is looking for. http://diamonds.pricescope.com/fnc1.asp

This is exactly the AGA-chart, which he already found. And true, this works well, unless you are dealing with AGS-graded diamonds, which are cut, starting from a different perspective. In that case, the AGS-grade rules.

On a more general note, there are clear reasons why DIY-cut-grading, based on numbers is so difficult in princess-cuts.

First, unlike in rounds, a princess has two basic pavilion angles and two crown angles. It is very unusual to get the info on all four angles from a vendor. Even the Sarin- and OGI-measurements do not give all these angles in the summary of the measurement. To get them, one needs to have a full 3D-scan, not just a summary.

Even more important, in rounds, there generally is little variation within the same angle. In princess-cuts, this difference within the same angle can be enormous. Take for example, the P1-angle. It is not uncommon to have princess-cuts with an average P1 of 61°, where three angles are 59.5° and the fourth is 65.5°. This is a classic example of how a cutter can hide weight in a princess-cut. The resulting info of an average angle of 61 is useless, and with the variation in angles, light performance is much more difficult to predict and will definitely be less symmetrical.

Therefore, in princess-cuts, I think it is very important to know at least one of her parents, with the king being the cutter and the queen being the vendor.

Live long,