Puzzling Comments about Holloway Cut Adviser

[La Jolla]

Recently, a consultant at Whiteflash told me over the phone that she prefers round diamonds that rate 1.0 to 1.9 on the Holloway Cut Adviser to diamonds that rate higher (i.e., lower than 1.0). She said that to her as well as to a few other consultants, diamonds that score 0.7 or lower on the HCA tend to "exhibit some darkness in the center of the table." Any thoughts on this?

If I''m comparing GIA- or AGS-certified diamonds online, all things being equal should I go for the stone with the lowest HCA score?

If a GIA-certified diamond has a cut grade of Excellent and an HCA score of 1.9, and a second similar GIA-cert diamond has a cut grade of Very Good but an HCA score of 0.8, which would you buy if they were priced the same?

 

[kenny]

I'd not base my decision on only that.

Post IS and ASET pics and the specs.

Do not reveal weight, color or clarity if you want to keep these 2 diamonds private so they don't get sold out from under you.

 

[Regular Guy]

Garry agrees (read quality only)
Yes, basically, you want to have more info as Kenny suggests
many older posts on this topic
but the HCA doesn''t provide a sharp enough pencil to allow you to have preferences between 0 - 2...as much for what''s posted in especially a GIA (vs AGS) cert about the diamond...making the photos Kenny speaks about more valuable for a closer look.

 

[Garry H (Cut Nut)]

Date: 9/23/2009 12:11:12 AM
Author: Regular Guy
Garry agrees (read quality only)
Yes, basically, you want to have more info as Kenny suggests
many older posts on this topic
but the HCA doesn''t provide a sharp enough pencil to allow you to have preferences between 0 - 2...as much for what''s posted in especially a GIA (vs AGS) cert about the diamond...making the photos Kenny speaks about more valuable for a closer look.

Kenny and regular guy gave you good advice and WF are telling the truth.

 

[La Jolla]

Thanks all three. I''m discovering that, besides Whiteflash, very few online vendors that I''ve come across will offer you Ideal-Scope and ASET images. What to do.

My question still is, why is it that diamonds that score 0.7 or lower on the HCA tend to exhibit some darkness in the center of the table, according to WF?

My other question for Garry was, If a VG cut GIA stone scores much higher on the HCA than one certified as an Excellent cut, and you don''t have IS and ASET, all other things being equal is it better to go with the graders (i.e., the Excellent cut) or with the HCA score?

Thanks. A bit of a newbie here.

 

[Allison D.]

LaJolla, the HCA isn''t a ''best-better-good'' system, so a lower score isn''t better than a higher one.

It''s more of a ''pass-fail'' concept - those under 2 pass; those above 2 don''t pass. This is because the HCA isn''t meant to be a selection too; it''s meant to be rejection based, with the goal being to help you narrow down your field of possible candidates to the stones most likely to perform well.

That said, it has been noted by many over the years that as the score drops below .6-.7, the diamond may lack a bit of contrast causing the stone to possibly have a bit of darkness under the table. It''s not a given that every diamond scoring in that range will, it''s more a benchmark for saying "when the score drops here, pay a bit of extra attention to this element."

If both of the stones you''re considering are at the same vendor and inhouse, your best bet is to ask your SA to have the two stones compared visually. Part of the benefit in working with a trusted jeweler is tapping in to their expertise. We''re happy to make those comparisons for people and provide our honest opinions, and I know many of our colleagues here do so gladly as well.

 

[Paul-Antwerp]

I respectfully and fully disagree with Garry and the WF-rep, while I find Kenny''s and Ira''s answer much more correct.

The reality is that the information upon which the HCA works is limited (not a sharp enough pencil, like Ira describes) to make such a blanket statement. Statistically, the chance of a HCA-score below 1 shows some central darkness is higher than with a score between 1 and 2, but considering that the HCA is an initial rejection-tool, it should not be used to make such blanket statements on a particular stone.

It is the same as saying that men run faster than women. Correct. But, on my last 10K, I was 15 minutes behind the first woman, which evidently makes her a faster runner.

Therefore, in your comparison of these two stones, nobody is capable of actually saying that one is actually better than the other without more information. It saddens me that highly respected people give the opposite impression here. Kudos to Kenny and Ira for doing better.

Live long,

 

[Paul-Antwerp]

I posted around the same time as Allison. Thank you, Allison, for bringing up the correct perspective.

 

[La Jolla]

Thanks, Allison and Paul, particularly for Allison''s very clear explanation and Paul''s concise summary "Nobody is capable of actually saying that one is actually better than the other without more information."

Paul, regarding your statement that "It saddens me that highly respected people give the opposite impression here. Kudos to Kenny and Ira for doing better." I think everyone here has wisely cautioned me to use the HCA as a limited tool, part of a larger data set. No one gave me the opposite impression.

Thanks all, La Jolla