AGS0 but HCA only "Good/Very Good"?

[Mal]

I'm interested in this diamond, but I'm concerned about the results of the HCA.

AGS
2.0ct
SI1
I
Table 57.2
Depth 62.2
Crown 35.3
Pavilion 41.1
Light Performance 0
Proportion Factors:0
Polish: Excellent
Symmetry: Ideal
8.04x8.07x5.02

I don't have an ideal scope. The HCA gives it a 3.7. How can AGS give it two 0s and it scores so high on the HCA? Realistically speaking, will I be able to tell the difference between this diamond and a 1.5 HCA scoring diamond under most lighting conditions? I plan on putting it in a ring and I just want a nice sparkly diamond. Thanks!!!

 

[belle]

can you post the grading report?

 

[Mal]

Here is the certificate:

 

[Lynn B]

This diamond would be considered by many to be steep/deep. The HCA "penalizes" pav angles over 41. IMHO, it's a little deep, too, which affects spread and diameter. It looks to me like the cutter worked pretty hard to retain enough weight to get the stone to (the magic) 2 carat mark. (Remember, it's in his best financial interest to do that!)

Also, this diamond is not an AGS-0. It is an AGS-1 (which is considered "Excellent" but not "Ideal" [by AGS standards] ) Actually, it is the first AGS-1 I have ever seen a cert for.

I would be interested to hear what you think of it -- are you able to see the diamond in person and observe it in various lighting situations? I am sure it is a lovely diamond, head and shoulders above most RBs out there. But it ISN'T an AGS-0, and it did score pretty well over 2 on the HCA. If you have seen it and it is a killer, OR if it is a super good price (it's certainly a GREAT size!) -- it may still be a good diamond to consider. But personally... I'm a hair-splitter

and I think I'd keep looking.

Just my VERY humble 2 cents!

 

[belle]

to answer your question about whether or not you would be able to tell the difference between a stone scoring 3.7 and one scoring 1.5, there is no way to tell. everyone perceives what makes a diamond ''beautiful'' differently. chances are there would be differences between the two that you would pick up but whether or not it is worth it $$$ wise is up to you. there should be a good difference in price between an ags1-2 and an ags0 and that is what the hca is accounting for. i would not pay a premium for this stone if you could have an ags0 for the same amount.

 

[Mal]

I haven''t seen the diamond in person, but I''m considering sending it to an appraiser in my area. I could get it for $13,500. Would that be a good price? Thank you for your help!

 

[Lynn B]

Date: 1/24/2006 2:43:53 PM
Author: Mal
I haven''t seen the diamond in person, but I''m considering sending it to an appraiser in my area. I could get it for $13,500. Would that be a good price? Thank you for your help!

FYI, a few months ago I got a killer 2.36 AGS-0 J/SI2 for $14K.
An independent appraiser is a good idea. It''s up to you at this point if you want to continue to pursue this diamond or just look elsewhere. If you do pursue it, please let us know what you thought of it, and if possible, take some pictures. We don''t get too many AGS-1s in these parts!

THANKS!

 

[diamondlil]

I asked an appraiser (well-known here at PS) last year whether he thought (knowing I''m a PS junkie) that I would be able to see the difference between an AGS0 and an AGS1 stone with my naked, unaided, un-ideal-scoped eyeballs, and his honest answer was "most likely not." An AGS1 such as the one you are considering is going to be a gorgeous diamond.

That being said, I do see that with this particular stone you are considering, it is on the deep side, and you will be sacrifing a bit of diameter because of it. If this diamond was a bargain, it would still be something to consider, but at $13,500, I personally would pass. The cutter kept that weight at the 2 ct mark for a reason -- more $$ per carat. So unless you are getting this 2 ct stone for less than a 2 ct price, I think you can do better.

Just my 2 cents.

 

[valeria101]

Date: 1/24/2006 1:39:59 PM
Author:Mal

How can AGS give it two 0s and it scores so high on the HCA?

Oddly enough, the same research went into both systems (HCA and AGS) - only the 'executive decision' of where to make the cut between grades turned a tad different. Since AGS faces more direct commercial concerns than the little random HCA plug on this site... I'd go with the HCA

Realistically speaking, will I be able to tell the difference between this diamond and a 1.5 HCA scoring diamond under most lighting conditions?


Good Q. You may find it asked and answered in older posts too. As far as I get this: the HCA is not supposed to predict exactly what the optics of every diamond are, partly because the measurements going into those scores are not 100% exact. Also, some details of the cut do not get mentioned in the HCA input at all (e.g. minor facets, indexing...). Basically, there is some chance that this stone is a charmer with a unfair HCA score.

One more thing: about the AGS cut grade - the HCA score is comparable with the 'Light Performance' grade on the AGS report (which is tops for the stone, as you say). The finish which finally downgraded the total AGS cut grade from 0 to 1 is not a concern of the HCA at all, and I would agree any day with the opinion that this does not affect the appearance of the stone in any way.

I wish there was an IS picture - hopefully confirming that the stone is indeed faultless. IMO, it has a good chance to turn out that way.

My 2c.



Is there no alternative with w/o debatable stats?

 

[MissGotRocks]

Doing a quick search at the top of the page there were four 2.00 stones, I, SI1, AGS0, for 13,700-13,900. For a couple hundred more, you would have an AGS0 stone. That niggling doubt about what it could have been may be enough to make paying the additional $$ worthwhile.

 

[Mara]

Personally I think yes you will see a difference in a stone scoring 3.7 and 1.5, depending on the numbers....my old stone used to score around 2.8 on the HCA and my new stone under 2.0 and it was like night and day. I would probably never buy a stone over 2.0...just my own experience. With the abundance of stones out there typically there is no need to ''settle''. Good luck!

 

[Mal]

Thanks for all your input! I''ve decided that this is not the stone for me. Thanks again!

 

[MissGotRocks]

Hang in there Mal! Just means something better is right around the corner for you! Let us know what you come up with - good luck!

 

[Regular Guy]

Actually, I''m hoping one of those smart cut guys will come on and explain this one.

I had thought that AGS0 for proportions was a clear subset of the HCA 0 - 2, basically. Then, I ran the numbers on this one to see for myself, and although the proportions grade on the cert pictured here is clearly 0, the "spot" where the cross hairs meet for crown & pavilion is way outside of the box drawn on the grid represented on the HCA chart, making the position of the cross hairs consistent with the higher score of 3.7, yes, but it''s not understood by me why the position of this AGS0 stone lies outside of the represented AGS0 box.

Was there a miscalculation of how AGS0 was to be calculated, making the represented box on the HCA chart not a true picture of how AGS is scoring proportions defined as ideal?

I am a bit puzzled by this one.

 

[tlikinim]

Also, this diamond is not an AGS-0. It is an AGS-1 (which is considered "Excellent" but not "Ideal" [by AGS standards] ) Actually, it is the first AGS-1 I have ever seen a cert for.

But the proportions are "0". What makes it a "1" is the polish rating which we know has nothing to do with light return. And this stone was graded in December 2005, which means the new and improved AGS proportion guidlelines were used, which are supposed to be better than pre August 2005 AGS 0 graded stones.

This topic is very interesting to me. I want to buy into the HCA theory because it''s simple and easy to use, but here is an example of where things don''t quite match up, as it appears it should. Just my two cents. I''m still learning about all of this.

 

[He Scores]

Here''s a tip diamond shoppers. This isn''t etched in *ahem* stone and not 99% accurate but it''s a worthwhile "rule of thumb" ......


It''s rare that if a stone hits exactly on 1.00 or 2.00, etc. that it will be a "premium" cut.

Usually the cutter had to perform a weight saving techique (read, comprimise on the make) to achieve this.

Not all the time, but it''ll save you time on researching stones to look at stones over or under the exact weight if quality of cut is what you''re after.


Bill

 

[Mara]

" I want to buy into the HCA theory because it's simple and easy to use, but here is an example of where things don't quite match up, as it appears it should."

___________________

While I agree that the HCA can be a good tool but is not precise in ALL situations, in this stone's situation, it gave a score I would expect to see based on the diamond's numbers. That depth on the stone is not a good one for me, and the crown angle and pav angle combo are not appealing either. So even if HCA was not involved here, I would have passed this stone up anyway if I was shopping.

When anyone is shopping, they should never blindly say oh AGS0 means a great stone. Just as they should never say oh the HCA gave it a 0.8 so it's a great stone. Don't solely rely on one thing, not even the numbers, to tell the whole story. But for me seeing the numbers and then the corresponding HCA score, as a virtual purchase on this it would not even make my final top 10 cut if I was shopping.

That said, if the original poster SAW this stone and said it was an ABSOLUTE KNOCKOUT, and loved it, well then numbers and the HCA are tools they may not be interested in. But for me personally...I know there are enough stones out there to find what you want and not compromise on anything if you can just be patient.

 

[valeria101]

Date: 1/24/2006 9:30:46 PM
Author: Regular Guy


Was there a miscalculation of how AGS0 was to be calculated, making the represented box on the HCA chart not a true picture of how AGS is scoring proportions defined as ideal?

I e-mailed Garry about this yesterday. ''Guess he''s got better things to do.

Didn''t they (the Cut Group) provide the background research for the new & improved AGS grades? If so... whatever glitch is there should be done with asap.

Honestly, what''s that white patch good for anyway? If ''guessing'' the probable AGS grade of a non-AGS graded diamond is of interest, that probably deserves it''s own discussion somewhere. All more so since now the AGS cut grade implies more complex input than the HCA.

Just IMO.

 

[Garry H (Cut Nut)]

Hi All
Sorry it took so long Ana - (still have you PM opened).
V Busy day yesterday, and it is a holiday here today.

I would think this diamond would die when it gets dirty.
And if you saw it loose and light was gwetting in the pavilion then it would look great.

AGS charts are for cutters to enable them to safely cut to their guidelines Ira. It is possible to achieve AGS 0 outside the recomended proportions - and maybe this stone has some girdle painting that could effectively lower its main facet angle effects (i.e. creative cutting, which AGs encourage).

An ideal-scope photo would help.

Finally the spread is about 3% down - smallish but not a disaster.

 

[valeria101]

Date: 1/25/2006 5:58:55 PM
Author: Garry H (Cut Nut)


Sorry it took so long Ana - (still have you PM opened).
V Busy day yesterday, and it is a holiday here today.

Thanks for the reply at a busy time





AGS charts are for cutters to enable them to safely cut to their guidelines. It is possible to achieve AGS 0 outside the recommended proportions ...

Ouch!

My bad... So... HCA should not be used to second-guess the new AGS grades?

 

[Regular Guy]

What holiday is it, Garry?

Thanks, Ana, for helping to continue the exchange. Good response.

Garry, your turn.

Thank you both and all.

 

[Garry H (Cut Nut)]

Date: 1/25/2006 7:52:46 PM
Author: Regular Guy
What holiday is it, Garry?

Thanks, Ana, for helping to continue the exchange. Good response.

Garry, your turn. I have no more to add, unless you all care to check out your >41 / 35 diamonds with an ideal-scope once they are dirty - then clean them and do the same test?

Thank you both and all.

Australia Day - our version of independance day I guess.