Need Advice!!! Does the dimensions fit the AGS 0 cut?

[kamahsutra]

Before I start with my question, I just wanted to let the PS forum/community know what a great asset they are to consumers that are new to diamond shopping. I found this site when I was researching what I needed to know for purching a diamond e-ring, and I''m still in the process. I really enjoy reading through the various threads and learning as much as I can.

Here is my situation:

I''m looking at a diamond that I am about to purchase, and it''s a from a very reputable retailer. The only dilema is that I cannot see the stone first hand (time and distance) prior to purchasing it, and the retailer does not send Idealscope photos or anything of that nature. So the only thing that I am left to work with are the dimensions of the cut from the certificate. Here are the dimensions:

Depth: 60.6%
Table: 56%
Crown angle: 34
Pavilion angle: 40.7

This scores 0.7 in the HCA. From what I''ve read on the forums here, a good rule to follow when you can''t see the stone, is to find one that fits into the GIA and AGS Excellent/Ideal cuts. When I punch these numbers into the HCA and generate the graph, it is clearly within the GIA Excellent box, but it''s very borderline on the AGS ideal box. Plug these numbers into the HCA and you''ll see what I mean.
I''ve doublechecked the dimensions with GIA Facetware graphs, and it''s confirmed.
I''ve also compared the dimensions with the AGS 0 range and it fits in as well, however, it''s so borderline on the AGS box outline in the HCA.

My question are:
Does this dimensions on this stone fit the AGS ideal range?
Is it not fitting into the HCA AGS ideal box outline simply because of how the software plots into the graph, and it''s a limitation of the resolutions of computer screens?
What do you think of the dimensions of this stone?

Please give me some advise. Thanks.

 

[stone-cold11]

It is fine, the pavilion angle are an average of 8 facets, round to nearest 0.2 degree interval by GIA and the crown, another 8 facets round to nearest 0.5 degree. So there is a spread and also the HCA I believe is develope in 0.1 degree interval.

The HCA score looks good.

 

[Lorelei]

Date: 1/29/2009 1:32:09 PM
Author:kamahsutra
Before I start with my question, I just wanted to let the PS forum/community know what a great asset they are to consumers that are new to diamond shopping. I found this site when I was researching what I needed to know for purching a diamond e-ring, and I''m still in the process. I really enjoy reading through the various threads and learning as much as I can.

Here is my situation:

I''m looking at a diamond that I am about to purchase, and it''s a from a very reputable retailer. The only dilema is that I cannot see the stone first hand (time and distance) prior to purchasing it, and the retailer does not send Idealscope photos or anything of that nature. So the only thing that I am left to work with are the dimensions of the cut from the certificate. Here are the dimensions:

Depth: 60.6%
Table: 56%
Crown angle: 34
Pavilion angle: 40.7

This scores 0.7 in the HCA. From what I''ve read on the forums here, a good rule to follow when you can''t see the stone, is to find one that fits into the GIA and AGS Excellent/Ideal cuts. When I punch these numbers into the HCA and generate the graph, it is clearly within the GIA Excellent box, but it''s very borderline on the AGS ideal box. Plug these numbers into the HCA and you''ll see what I mean.
I''ve doublechecked the dimensions with GIA Facetware graphs, and it''s confirmed.
I''ve also compared the dimensions with the AGS 0 range and it fits in as well, however, it''s so borderline on the AGS box outline in the HCA.

My question are:
Does this dimensions on this stone fit the AGS ideal range?
Is it not fitting into the HCA AGS ideal box outline simply because of how the software plots into the graph, and it''s a limitation of the resolutions of computer screens?
What do you think of the dimensions of this stone?

Please give me some advise. Thanks.

Welcome!

The diamond has great potential, do you have an Idealscope image for it? It isn''t essential to have the numbers overlap the GIA/ AGS boxes although that is the bullseye it isnt'' mandatory, plus the HCA isn''t used for selecting diamonds but for rejection - your diamond has excellent proportions and an IS is the next important step if you can get one.

 

[kamahsutra]

Thank you both for your replies.

I don''t think that they''ll provide me with an Idealscope picture. As they do not get into this type of market, and they''re a very reputable retailer.

I''m hoping Mr. Holloway himself can answer question #2, if it''s neccessary.

I''m really hoping to get this one, and post the pics when I get it!!!

 

[Todd Gray]

Date: 1/29/2009 1:54:45 PM
Author: kamahsutra
I''m hoping Mr. Holloway himself can answer question #2, if it''s neccessary.

Well it''s like 7:00 a.m. in Australia right about now so Garry might pop in and comment, but let''s see if I can''t provide some insight in the mean time...

The diamond you are looking at is pretty much in the center range of the spectrum for the zero ideal cut proportions rating, it would be absolutely dead center if the crown angle were in the midst of 34.3 - 34.8 degrees (average 34.5) but 34.0 is certainly well within tolerance and worthy of consideration when offset with a 40.7 degree pavilion angle! Assuming that the average 40.7 degree pavilion angle is the result of a reasonably tight range of high and low measurements then the diamond is likely quite lively! The same premise holds true for the average 34.0 crown angle. Ask the seller for a Sarin / OGI / Helium computerized proportions analysis to be sure... They can always call the AGS or GIA for the results if they don''t have access to a machine themselves.

With that in mind, here''s what you''re seeing in the graph (attached).

Prior to June 01, 2005 the AGS proportions grade was based on a broad spectrum range and if the proportions of the diamond fell within that range, the diamond was considered to have Ideal proportions. The AGS figured out that cutters were abusing the concept of the proportions grade system (as outlined above in terms of the high and low range that results in the average crown and pavilion angle measurements stated on the lab report) by cutting the crown and pavilion sections with a broad swing from like 33.5 degrees up to 35.5 degrees and back down and back up again (like ocean waves) to obtain an average crown angle of 34.5 degrees and doing the same on the pavilion and this was resulting in the triangular outer girdle facets looking dark on diamonds that were getting an AGS Ideal rating for proportions... The AGS put a stop to the practice by fine tuning their rating system for the proportions grade and by adding a Visual Performance rating to their grading system.

At the top of the graph that appears with the HCA results it says "AGS 0 Candidates for 56% table in white outline" (outlined in yellow) and that means that this graph is only applicable for (round) diamonds with a 56% table diameter and that for the diamond to qualify for the zero ideal cut rating (indicated by the range of red as indicated in the upper right corner of the graph as indicated by the white arrow) the Crown Angle measurement must fall within 33 - 37 degrees BUT that the Pavilion Angle measurement MUST ALSO fall within the range of pavilion angle measurements that fall within the white outline as it corresponds to the crown angle and vice versa. So for a round diamond with a 56% table diameter and a 40.7 degree pavilion angle, the crown angle has to fall within a range of what looks to be about 33.7 - 35.0 degrees based on the graph provided with the HCA (I don''t have the actual AGS graphs on the computer I''m responding from). So this diamond isn''t really "at the edge" of the provisions specified by the HCA results, it''s actually well within it and as I''ve said, definitely worthy of further consideration!

 

[kamahsutra]

Thanks Todd, for a very detailed and good explanation. You may have just about covered most of my questions regarding the HCA, unless Mr. Holloway has something to add.

I''m going to ask the retailer if they can provide me with a Sarin report, which I doubt. But I''m certain I can trust their reports about the dimensions.

 

[Lorelei]

Date: 1/29/2009 3:32:31 PM
Author: kamahsutra
Thanks Todd, for a very detailed and good explanation. You may have just about covered most of my questions regarding the HCA, unless Mr. Holloway has something to add.

I''m going to ask the retailer if they can provide me with a Sarin report, which I doubt. But I''m certain I can trust their reports about the dimensions.

Todd''s great isn''t he???

 

[kamahsutra]

Lorelei, yes Todd is great! However, I''ve read many of your posts while reading through these forums and all of you veterans on Pricescope are grea and most helpful!!!

A round of applause to all of you.