Need advise on AGS Ideal 0 cut but high HCA score stone

[xiaohanzhu]

Hi Everyone,
I have the following stone on hold in bluenile.
http://www.bluenile.com/round-diamond-2-carat-ideal-cut-i-color-vs2-clarity_LD02515818
Depth: 61.9%
Table: 57.2%
Crown: 36.1
Pavilion: 40.9
I like everything about the diamond on the certificate, except when I ran the porportions in HCA, the score was 4.5. I am wondering if it is worth to take the risk and have it shiped to me to take a look. Your recommendations are highly appreciated. If I do decide to take the bite, anything I should look out for in this stone?
Thank you

 

[odbg]

personally, the hca tool is more of a rejection tool and most of the time it is accurate in weeding out diamonds.

A score that high would probably raise red flags with me and indicate a diamond that is leaky. The more sure way to tell is to get idealscope pics from the vendor and unfortunately, this is something BN would probably NOT do for you.

a purchase close to $30k is huge and i think it would be wise to lay down your money only when you are 100% sure of what you are looking at. no pictures no talk. That's my humble opinion on buying diamonds online.

Don't put yourself in a spot or take the additional risk where you need to return the diamond because it's not worth the trouble.

 

[John P]

I am surprised that this average angle combination received Ideal from AGSL. Diamonds with its basic numbers usually have enough leakage to fall out of the 0 light performance range. In fact the AGSL cut guidelines predict AGS2-3 in light performance for such a stone.

It's also worth noting that someone opted for an older DQD report (even though it was graded just over a month ago) rather than using the current AGSL Platinum Report which includes the diamond's ASET imprint. Choosing a report which omits the ASET doesn't boost my confidence.

 

[kristalulu]

Here are a few great stones within your budget of around $30K:
http://www.goodoldgold.com/diamond/8920/
http://www.goodoldgold.com/diamond/9133/
http://www.briangavindiamonds.com/diamonds/diamond-details/2.456-i-vs2-round-diamond-ags-bl-104057888001

 

[Regular Guy]

It's also worth noting that someone opted for an older DQD report (even though it was graded just over a month ago) rather than using the current AGSL Platinum Report which includes the diamond's ASET imprint. Choosing a report which omits the ASET doesn't boost my confidence.

That sort of analysis is why you paid to be here...


Ira Z.

 

[xiaohanzhu]

Looks like there is significant discrepency between AGS Ideal 0 and HCA <2. The following is another example with ASET imprint. I am wondering how could this stone be rated at Ideal 0.
http://www.bluenile.com/round-diamond-2-carat-ideal-cut-h-color-vs1-clarity_LD02124573

I am surprised that this average angle combination received Ideal from AGSL. Diamonds with its basic numbers usually have enough leakage to fall out of the 0 light performance range. In fact the AGSL cut guidelines predict AGS2-3 in light performance for such a stone.

It's also worth noting that someone opted for an older DQD report (even though it was graded just over a month ago) rather than using the current AGSL Platinum Report which includes the diamond's ASET imprint. Choosing a report which omits the ASET doesn't boost my confidence.

 

[John P]

First reaction: This doesn't look like an ASET I'd call Ideal.



Checking the AGS cut guidelines they list this proportions-combination as a candidate for AGS 5.



I went ahead and wireframe-simulated the measurements and can see why the prediction is 5.



But in this actual diamond's case, deviations from precise cutting appear to be helping it achieve a higher overall performance grade. As you can see in the wireframe-simulation there would be a ring of light-loss under the table if it were uniformly cut. But the amount of grey light loss on the report-imprint is slighter, replaced in much of the top by green and at 10:00 by red. Also, I suspect some creative brillianteering was done around the girdle to reduce edge-leakage from what we see in the wireframe-simulation. Despite that reduction there is still a lot of green on the actual-imprint. If someone had shown me this imprint I would have guessed it to be AGS3.

It's definitely a cool gemological case study because there is no doubt it was improved beyond the AGS cut guideline prediction. With that said, I would not pay the "Ideal" price for this stone. Especially since (arguably) the most important aspect of diamond beauty is scintillation and while we can extrapolate some things about scintillation from a robust ASET this one raises a lot of questions. For me, anyway.

Looks like there is significant discrepency between AGS Ideal 0 and HCA <2.

Not usually, although you've found some prime examples. There is always a discrepancy between HCA <2 and average pavilion angles over 41(ish) - usually for good reason.

Thanks for bringing these forward for discussion.

 

[Karl_K]

First reaction: This doesn't look like an ASET I'd call Ideal.

I agree.
Plus a slight scanner error could moved this stone from a 5 to 0 to ?.
I would love to see an actual ASET image for the stone.
These borderline stones are a real weakness in the AGS grading system because it is based on scan data.
The more twisted the facets the harder time the scanner has getting good measurements so errors likely go up.
Even if it scans it within the stated specs of the scanner you can still get GIGO with computer generated images/grades when you get to the edges and extremes..