Poor HCA scores for AGS-0/GIA ex --- WHAT''S THE DEAL?

[about2begin]

I have asked a local vendor to being in some stones for me. They are all either GIA ex-ex-ex or AGS-0 but on the HCA 2 of the 3 come back with really bad scores (5-6.9) and only one comes back at a 1. This mirrors the experience I''ve had with some other stones that I''ve asked to see (good GIA/AGS stats but a poor HCA)

My question is this: If the HCA is supposed to be predictive of a diamond''s qualities, and so too is the grading done by GIA or AGS, why would an ex/ags-0 come back with a horrid HCA score?

Am I misunderstanding the HCA? Are some AGS-0''s dogs?

 

[strmrdr]

What are the numbers for the diamonds in question?

Some GIA EX come back as being to steep/deep on the hca but it would be rare for a ags0 to if its the new style DQD report.

 

[AvusM5]

You have to see the stones in person.

I never researched online, browsed PS, nothing. All I did was go look at various, individual stones. Over the course of my exploration, I probably looked at 60 different kinds of stones. Some were dull, others were ridiculous!

I finally settled on the one I thought was the best performer... and it is OUT OF THIS WORLD!!!


Bottom line, all these numbers(depth, table etc.), GIA-ex this and that, AGS-0 etc. is all crap next to seeing them in person and judging for yourself.

 

[about2begin]

Stone #1: (GIA) 1.93 ct., F color, SI-1 clarity, Excellent Cut, Excellent Symmetry, Excellent Polish

Stone #2: (GIA) 2.05 ct., H color, SI-1 clarity, Excellent Cut, Excellent Symmetry, Excellent Polish

Stone #3: (GIA) 2.01 ct., F color, SI-2 clarity, Excellent Cut, Excellent Symmetry, Excellent Polish



Stone #1 : HCA 5.5 (Good, Poor, Fair, VG)

Stone #2 : HCA 1 (Ex., Ex., Ex., Ex.)

Stone #3 : HCA 6.9 (Fair, Poor, Poor, VG)


The AGS-0 was from a different vendor and I don''t recall the number offhand. The price for stone 2 was estimated at $18-19k

 

[neatfreak]

There is a lot variation with GIA ex/ex stones too, AGS is more reliable as Storm said...the HCA was also made by a person and reflects their preferences. I would read all the caveats/user guide with the HCA, it will explain a lot.

 

[neatfreak]

Those stones are all GIA and unfortunately it isn't uncommon for a GIA ex/ex to end up with a poor HCA score. Have you seen these stones in person? Do you have the stats you entered into the HCA?

 

[about2begin]

I haven''t seen them in person but that''s because I have been wasting a lot of time seeing stones that don''t meet my standards. I''ve finally found a dealer who will bring in exactly what I want before I go in to his shop. I''m basically just pre-screening stones at this point b/f I look at them on Thursday.

 

[about2begin]

Also, would a poor HCA on a gia ex make someone pass on the diamond?

 

[Lorelei]

Date: 10/22/2008 1:31:51 PM
Author: about2begin
Also, would a poor HCA on a gia ex make someone pass on the diamond?

Because the criteria for GIA Excellent cut grade is broad, and can allow for some less desirable combos in some cases. Also don't use the HCA for selecting stones, it is used for eliminating lesser performers.

 

[AvusM5]

Again, I'd have to see it in person.

I looked on the HCA on PS for two stones after I had bought the stone I have now for my S.O. ... both of those other stones received over 2.5 (I think one was 2.8 and the other 3.1) on the HCA with "Good" ratings scattered. But when I saw them in person, they were extremely nice stones with tremendous sparkle and fire, though not as nice as the one I bought

. Just goes back to my original statement that you have to see them first.

 

[Allison D.]

Date: 10/22/2008 1:16:20 PM
Author:about2begin
I have asked a local vendor to being in some stones for me. They are all either GIA ex-ex-ex or AGS-0 but on the HCA 2 of the 3 come back with really bad scores (5-6.9) and only one comes back at a 1. This mirrors the experience I've had with some other stones that I've asked to see (good GIA/AGS stats but a poor HCA)

My question is this: If the HCA is supposed to be predictive of a diamond's qualities, and so too is the grading done by GIA or AGS, why would an ex/ags-0 come back with a horrid HCA score?

Am I misunderstanding the HCA? Are some AGS-0's dogs?

The current AGS0 grading structure is not predictive - it's based on 3D light performance measurement done on the actual stone. As such, if you're working with an AGS0 stone that has a light performance grade, it's not predictive.

If you are looking at an older AGS0 (meaning the 2d parameter based metric), then it's entirely possible the HCA score to come back somewhat high. In days of old, AGS' 0 cut grade was based on the measurements being within certain angle tolerances but didn't factor the relationship between the crown/pavilion angles.

With GIA, their EX range is so wide that it's possible to run into steep/deep combos at the outer edges of that range, and the HCA penalizes such stones.

Do keep in mind the purpose of the HCA; it's meant to help narrow down your candidates to those *most likely* to be top-performers. While a useful tool for what it does, it has limitations. It assumes a perfectly symmetrical stone and a uniform girdle; it also predicts based on a few measure points, not on the actual stone itself.

It's a great tool to help those who want to whittle down a wide pool of stones to a few probable strong candidates. It doesn't replace seeing the stone yourself, and it isn't perhaps as informative as an ASET image or Idealscope image which considers the *actual* stone.

 

[about2begin]

Thanks to everyone!

When I see the stones in person everything (aside from REALLY poor performers) looks the same to me. Sure, it''s sparkly -- it''s a diamond. I''m trying to get the best sparkle, the best light return, the best performance in day-to-day situations (not just in a store setting). I was thinking that the HCA was designed to help predict which stones would fail to provide that.

 

[Allison D.]

If you''re viewing in a jewelry store rife with jewelry store lighting, that can be a big reason they look similar. That lighting is designed to make stones look sparkly and appealing.

I''d suggest trying to see a few stones in other conditions. Ask to see the stones next to a window with diffused daylight. Ask to turn off the overhead jewelry lights. Look at the stones in an area that''s dimly lit.

 

[about2begin]

Thanks, Allison. My friend and I were trying to cup our hands over the stones to simulate that type of lighting environment.

Also, how does $18-19k sound for a 2.05ct GIA SI1 H with a solid HCA (let''s just assume it looks OK in terms of performance and that it is eye clean) -- is this in the right ballpark?

 

[AvusM5]

Take the stones away from the "fake" lighting in the stores ... even the most crap stones will look like a million bucks with the lighting they have in some places.

What I did was take the stone to the darkest places of the store, yes, even by the bathrooms to view with natural lighting or even under some sunlight. That''s when you truly see the beauty of the stone and difference among a group of them...

 

[JulieN]

18-19 sounds cheap/good deal for an ideal stone in a B&M.

magnifique: http://www.jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-981003.asp?b=16&a=12&c=77&cid=131

 

[about2begin]

Date: 10/22/2008 2:16:54 PM
Author: JulieN
18-19 sounds cheap/good deal for an ideal stone in a B&M.


magnifique: http://www.jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-981003.asp?b=16&a=12&c=77&cid=131

Have you purchased from James Allen? That stone''s plot looks pretty messy but assuming that it is eye-clean, it''s a nice price too. Plus the color is a bit better.

 

[JulieN]

oh, whoops. I somehow thought you said G color instead of H, so that''s what I searched for. You can type James Allen into the search box at the top. They are one of the more popular vendors with PS posters. The plot doesn''t mean anything...sometimes a messy plot with lots of small inclusions is better than a couple of giant ones. You''d have to ask if it''s eyeclean.

 

[Allison D.]

Date: 10/22/2008 1:50:17 PM
Author: about2begin
Thanks, Allison. My friend and I were trying to cup our hands over the stones to simulate that type of lighting environment.

Also, how does $18-19k sound for a 2.05ct GIA SI1 H with a solid HCA (let''s just assume it looks OK in terms of performance and that it is eye clean) -- is this in the right ballpark?

Honestly, it sounds VERY low for a B&M store. Even among online vendors, which tend to be more competitive than local stores as a rule, similar stones are running in the $23-24K-ish range. Locally, I''d expect the price to be a bit more. If it''s a GIA, I''d suspect it might be on the weaker end of their EX range, but wouldn''t know that without more info.

 

[about2begin]

Date: 10/22/2008 3:12:58 PM
Author: Allison D.

Date: 10/22/2008 1:50:17 PM

Author: about2begin

Thanks, Allison. My friend and I were trying to cup our hands over the stones to simulate that type of lighting environment.


Also, how does $18-19k sound for a 2.05ct GIA SI1 H with a solid HCA (let''s just assume it looks OK in terms of performance and that it is eye clean) -- is this in the right ballpark?

Honestly, it sounds VERY low for a B&M store. Even among online vendors, which tend to be more competitive than local stores as a rule, similar stones are running in the $23-24K-ish range. Locally, I''d expect the price to be a bit more. If it''s a GIA, I''d suspect it might be on the weaker end of their EX range, but wouldn''t know that without more info.

Well this isn''t really a B&M store per se. This is a guy who sells to local stores like Steven Singer and he has worked with a handful of my friends in the past so he sells loose stones to people referred to him at a similar price to what he''d charge a B&M store bringing in the same stone. He just went off the Rappaport report and estimated about $8500-9000/ct

 

[Allison D.]

Date: 10/22/2008 3:23:12 PM
Author: about2begin

Well this isn''t really a B&M store per se. This is a guy who sells to local stores like Steven Singer and he has worked with a handful of my friends in the past so he sells loose stones to people referred to him at a similar price to what he''d charge a B&M store bringing in the same stone. He just went off the Rappaport report and estimated about $8500-9000/ct

About2, I can appreciate wanting to get ''a deal'', but sometimes ''deals'' end up costing more than you expect.

You are proposing to buy from someone who claims to be a wholesaler, but by definition, wholesalers do not sell to the public....period. If his retailers found out he was undercutting their business, I''m guessing they''d be less than thrilled.

You''re considering laying out just shy of $20K.....far from an insignificant amount. How well protected are you if you aren''t happy your purchase? Is he willing to do what actual retailers do and provide you with a reasonable return period, meaning return for refund if that''s what you want? What if you need service after the fact...is he structured to provide it?

Wholesalers don''t sell to the public at the same price they sell to retails at....they don''t sell to the public at all.

 

[about2begin]

Date: 10/22/2008 3:42:04 PM
Author: Allison D.

Date: 10/22/2008 3:23:12 PM

Author: about2begin


Well this isn''t really a B&M store per se. This is a guy who sells to local stores like Steven Singer and he has worked with a handful of my friends in the past so he sells loose stones to people referred to him at a similar price to what he''d charge a B&M store bringing in the same stone. He just went off the Rappaport report and estimated about $8500-9000/ct

About2, I can appreciate wanting to get ''a deal'', but sometimes ''deals'' end up costing more than you expect.


You are proposing to buy from someone who claims to be a wholesaler, but by definition, wholesalers do not sell to the public....period. If his retailers found out he was undercutting their business, I''m guessing they''d be less than thrilled.


You''re considering laying out just shy of $20K.....far from an insignificant amount. How well protected are you if you aren''t happy your purchase? Is he willing to do what actual retailers do and provide you with a reasonable return period, meaning return for refund if that''s what you want? What if you need service after the fact...is he structured to provide it?


Wholesalers don''t sell to the public at the same price they sell to retails at....they don''t sell to the public at all.

He said he would allow for returns within 30 days. I''m comfortable with this vendor because he''s worked with several of my friends and they have all had glowing experiences. Honestly, I feel that the extra $3000 (give or take) that I would pay with some of the PS vendors and other B&Ms isn''t really worth it. A diamond is a diamond.

Am I wrong about that? Should I pay the extra money for service and reputation?

Also, I don''t really care what his other buyers would think. I won''t broadcast this information so I don''t they''ll find out. He mentioned that he didn''t care if a local B&M paid him for the stone or I did. He also said he could bring in anything I wanted to see in person. I can always ask him for other options if this doesn''t pan out.

 

[Allison D.]

Are you wrong? I don't think anyone could say since everyone's personal level of risk tolerance varies.

I don't know what your level of risk tolerance is; I can only tell you that mine is pretty conservative, and that's where my advice stems from. I personally wouldn't be comfortable putting that amount of money at potential risk in the name of getting a 'deal'. I've seen too many 'friend of a friend' deals lead to disappointment.

However, you seem very comfortable with this avenue, and if you are, that's what matters. Since you are very comfortable with him, perhaps he'd also be able to help you better understand about why GIA EX stones may widely vary in performance.

Best of luck to you in your search.

 

[:)]

I would suspect they are on the steeper/deeper side.
What are the crown angles, pavillion angles, depth, table, diameter, and girdle thickness?

You mentioned that they were gia ex or ags0, then mention that there were 3 of them with two having bad scores - all 3 you listed were gia - were any of the ones with 'bad' hca scores ags0?