AGS 0 vs. GIA "excellent"

[valeria101]

This one should have been attached to the post above:

 

[valeria101]

That, would be nicely available online here (in case the reasoning is right, and anyone bothers!).

Anyway, the case seems to have been chosen as a neatly targeted example of 'borderline' HCA grades.

Besides, it wouldn't take this much work to decide which is the 'worst' and 'best' HCA score possible for a set of GIA rounded numbers: given the crown / pavilion tradeoff, the most different - for better or worse - possibilities would be the shallow-shallow and steep-deep.

... which can be plugged into HCA and tried on the DC too - something I was going to move on into if you, Garry wouldn't have done it before.

Now, the star and LGF are rounded too, but...and the extreme combinations would look like this (there should have been four more... overlooked).

Now, if this is an example of worst case scenario, how terrible can that be? Insofar, something like the bottom-left case in the picture below look the worst: but that's quite a giant picture compared to the objects at stake. Adding to this the not quite popular observation that the IS images tend to overstate leakage, things don't look all that bad. Also, I wonder if perfect optical symmetry (as these models have but GIA Ex. diamonds do not have to) doesn't emphasize these 'faults' quite a bit. A more 'random' cut would not have distinct patterns of leakage (or distinct patterns of anything for that matter).

 

[Garry H (Cut Nut)]

I think there is no substitue for a vendors scan results Ana - GIA''s data is, as you have shown - too broad to be useful with HCA when hair splitting near a HCA boundary.

 

[valeria101]

Date: 4/11/2006 7:29:10 AM
Author: Garry H (Cut Nut)

I think there is no substitute for a vendors scan results Ana - GIA's data is, as you have shown - too broad to be useful with HCA when hair splitting near a HCA boundary.

But this borderline this is a 'worst case', right? (worst case of fitting between GIA's cut grading system and the HCA - 'guess there are worse GIA 'Excellents').

Wonder how many AGS0 candidates (or HCA 0-2 candidates) are among GIA Ex-Ex? From a few searches it looks like quite a few. Is AGS loosing business ?

 

[strmrdr]

My pick without more info would be:


round brilliant, new GIA "excellent cut," 1.23ct, eye clean SI1, I, excellent polish, very good symmetry, 61.1 depth, 56 table, 33.5 crown angle, 41 pavilion angle, no fluorescence, HCA score of 1.

Even if the data is rounded taking both extremes that it could be still makes for a nice diamond.

 

[GeoAtl]

Thank you all so VERY MUCH for your opinions and posts. Keep ''em coming! It sounds like most people here would take a higher HCA score over a new AGS 0 certification. In this particular case where the GIA diamond has a better HCA score than the AGS one, why is the market value of the latter higher?

 

[aljdewey]

Date: 4/10/2006 7:57:42 PM
Author: GeoAtl
aljdeway, please note:

1) the wholesaler has stated that both stones are eye-clean. Under the circumstances, I don''t see any difference between being forced to rely on the wholesaler or the retailer; and

2) the stone I am considering is also a 2006 AGS 0 stone with light performance rankings.

In light of the above, what additional information do you think is essential before the final decision is made?

Geo, I did note what the wholesaler said. However, you should note that eyeclean is a descriptor and not a legal definition.....therefore, what someone else''s eyes may see as eyeclean may not be eyeclean to yours, if you are particularly clarity sensitive.

Hence my recommendation.....make sure you have a good return policy, and you should be fine.

 

[GeoAtl]

Noted and very much appreciated!

 

[Houseparty]

Date: 4/10/2006 8:13:39 PM
Author: GeoAtl
David, it seems like you and I are/were interested in essentially the same stones, so I actually used your stone''s stats and the price from the previous thread as a guide for myself. The GIA stone that I am looking at here would probably end up being priced within +/- $50 of your price.

What I am still trying to figure out here is whether an AGS 0 certification or a ''better'' HCA score is a better predictor of the stone''s performance. Along the same lines, the AGS 0 stone that I am considering is a few hundred dollars more expensive than a GIA stone with a higher HCA score -- why is that?

Hi,
The GIA you are considering has "excellent" polish compared to my VG, so that may be worth a few dollars...

Big picture, both stones will likely be very good performers and would make your lady very happy. You are looking at two very well cut stones, and saving significant $$$ compared to a super ideal branded.

Both GIA and AGS are desirable paper. AGS a little more so for reason found all over this forum. The AGS has "ideal" symmetry compared to the GIA "VG". Probably not discenable to the naked eye, but impacts value.

However, the stone does not know what the cert is. This AGS is probably on the edge of AGS0, while the GIA may be closer to true ideal proportions. The GIA rounding issues on their proportions are true, so that blurs the data on the GIA.

HCA has its own set of assumptions and preferences. Difference of opinions in marginal situations is a fact within the diamond world.

There is no right answer, a case can be made for either. Personally (and this reflects my personal preferences only), I would go with the GIA because that stone has a better spread, (61.1 vs 61.9 depth), sight unseen, Si1 makes me more comfortable, and as strmrdr said, even with worst case rounding, the GIA PA, CA and depth combos work well. Plus, you can save a few bucks...

I believe that both diamonds will sell in the next 30 days. If either stone were a "mistake" this forum would have told you...

Sincerely,
David

 

[Rhino]

Date: 4/11/2006 6:09:29 AM
Author: Garry H (Cut Nut)
GEO you are very safe with the GIA proportions - it is most unlikly that it would look bad - but the idea that you can model an accurate image from data that is rounded is not going to help you.
For instance the data I listed:

57.5% table, 35.25 crown angle, 40.9 pavilion angle, 57.5% star and 82.5% lower girdle?

GIA can round this to 57% or 58%, 35 or 35.5, 40.8 or 41, 60 or 55%, and 80 or 85%.
The stone on the left is modeled with the smaller of each #, and on the right uses the larger #'s.
There is a big difference in their respective ideal-scope images, and their performance and spread.

Too funny Garry. What are the odds of finding a diamond on the market that falls exactly between the measurements on each facet set?

 

[Rhino]

Good post Val. Hey ... a recent 35.1/41.2 stone came in (GIA Ex) that was a hella bright stone and the leakage that existed under the table was not even discernable. Stone was a 3.6 and hte comparison was next to a 1.0 except hte 1.0 had painted girdle facets.

Geo ... here is a model based on the GIA Report you forwarded to me in email. I thought I''d share it here too for any consumers wanting to see it for educational purposes. The details on the GIA Report were as follows...

6.91-6.97 x 4.24
61.1 depth
56 table
33.5 crown angles
41 pavilion angles (btw, seeing 41 coupled with 33.5 is nice!
55% stars
80% lower halves
thin to medium girdle

You''ll need to install the Gem Advisor software (free at this link). Tip: Install the software then open it up. This will associate .gem files in Windows. Then open the attached file directly underneath my post. To gain more insights about what it is you''re seeing in this file check out the email I sent ya.

The stats look very nice on this one.

The lower halves are pulled down to a length that would add a nice mix of pin flash with broad flash in direct lighting along with excellent brightness and fire. Since it is GIA Ex you are also assured of no painting and digging to the extent where it would impact optical performance as well.

The only question mark remaining in my mind is its optical symmetry/craftsmanship. This model shows near ideal optical symmetry and the actual stone may not be as optically symmetric. Otherwise ... looks good man. You''d just need to confirm that the clarity is fine with you and that there aren''t any other characteristics impacting its optical performance.

Kind regards,

 

[Paul-Antwerp]

Date: 4/11/2006 10:05:53 AM
Author: GeoAtl
Thank you all so VERY MUCH for your opinions and posts. Keep ''em coming! It sounds like most people here would take a higher HCA score over a new AGS 0 certification. In this particular case where the GIA diamond has a better HCA score than the AGS one, why is the market value of the latter higher?

I, and others, totally disagree with this assessment.

The new AGS-0 certification is based upon the actual 3D-scan of the diamond.

The HCA is based upon a few average numbers. In the case of these numbers coming from a GIA-report, these numbers are heavily rounded, on top of that. Therefore, the HCA-score is definitely less reliable.

Cut-wise, these 2 stones, are of similar quality, IF the GIA-figures are not all rounded towards the better direction.

Live long,

 

[belle]

Date: 4/11/2006 3:37:09 PM
Author: Paul-Antwerp

Date: 4/11/2006 10:05:53 AM
Author: GeoAtl
Thank you all so VERY MUCH for your opinions and posts. Keep ''em coming! It sounds like most people here would take a higher HCA score over a new AGS 0 certification. In this particular case where the GIA diamond has a better HCA score than the AGS one, why is the market value of the latter higher?

I, and others, totally disagree with this assessment.

The new AGS-0 certification is based upon the actual 3D-scan of the diamond.

The HCA is based upon a few average numbers. In the case of these numbers coming from a GIA-report, these numbers are heavily rounded, on top of that. Therefore, the HCA-score is definitely less reliable.

Cut-wise, these 2 stones, are of similar quality, IF the GIA-figures are not all rounded towards the better direction.

Live long,

i totally agree that we disagree with that assessment.

 

[GeoAtl]

I owe you guys an update. I had to go on several last minute business trips, so I didn't get a chance to finalize the transaction until just a few hours ago. I decided to go with the AGS diamond: I am quite confident that neither I nor my girlfriend/soon-to-be fiance would be likely to notice the slight difference in the spread and sparkle between the AGS stone and the GIA one. I do, however, sometimes notice a difference in color between H and I and, since both stones are eye clean, I just went with the higher color of the AGS one. The AGS stone also represents a truly outstanding value -- I got the price down to $5,100, when even its Pricescope price is over $5,500.

I just had an appointment with my appraiser and everything has checked out. The diamond is absolutely gorgeous, totally eye clean and the appraiser even commented that the cut is truly outstanding, even for an ideal stone.

Thank you all so very much for all the incredibly helpful and thoughtful insights and suggestions. I really truly appreciate them all!

 

[Rod]

Congratulations. I''m sure it will be totally spectacular. You know it''s a PS requirement that you post pictures (handshots are particularly welcome) of the finished ring.

Good luck and we''ll be looking for pics in the near future.

 

[Houseparty]

Date: 4/11/2006 1:43:02 PM
Author: Houseparty

I believe that both diamonds will sell in the next 30 days...
Sincerely,
David

Hi GeoAtl,
Congratulations, I was wondering how your situation played out. Nicely done

Which vendor earned your business?

I see that the 1.23ct GIA is no longer listed, so my predicition that they would both sell soon appears correct

Sincerely,
David

 

[GeoAtl]

Thanks, guys. Jud McMullen at Diamond.com initialy located both diamonds. Diamond.com has a merchant page on Fatwallet.com, which allows you to receive $250 off all diamonds priced over $4,000 (this is Diamond.com''s standard offer) plus 5.5% cash back through Fatwallet. The only caveat is that the diamond must be in Diamond.com''s online virtual database. Although the AGS diamond in question was not in the database (Jud located it through Diamond.com''s suppliers), I was assured that I would still be able to take advantage of the special by purchasing another similarly priced stone on Diamond.com and then having Jud manually substitute the one I wanted in its place.

While I was continuing to look for the right stone, I was contacted by Martin Sheffield at USACerted, who also offered me the same AGS stone but at a higher price. When I pointed out that Diamond.com''s price was lower, Martin said he could match it but not beat it, since, according to him, the profit margin on the stone was already quite low.

Once I made the decision to go with the AGS stone, I felt that Diamond.com, as the first vendor to locate it, deserved to get the business. After I told Jud that I was prepared to purchase the stone, Jud checked around and told me that Diamond.com would not let him substitute the stone, as he had originally intended to do, and could not for some technical reason place the stone in its online database. Jud also told me that since the GIA stone was in their online database, I could just purchase that one.

Since the AGS stone was my first choice at that point, however, I had to decline Diamond.com''s offer and purchased the stone through Martin. So, this is my somewhat convoluted story. I do feel badly for Jud, who, because of Diamond.com''s strange reluctance to add the stone to its database/let him substitute the stone, was not able to take credit for the purchase. The $250 off offer and 5.5% off certainly makes Diamond.com''s prices some of the best if not the best out there but with that come the strings. Martin, on the other hand, certainly demonstrated wonderful flexibility by matching the best price and offering good service.

Now I can finally order the Ritani Royal Crown setting I want -- I am not a huge fan of designer settings but it''s the only one I''ve found that has the classic knife-edged Tiffani setting look I am looking for. Solomon Brothers tells me that it''ll take 4 weeks to get it in, so I guess I''ll have to patient

 

[Houseparty]

Hi GeoAtl,
So Martin got the business. Sounds like he sold 2 similar stones to 2 similar customers. Thanks for the update.

Sincerely,
David