GIA Grades vs. HCA Tool (First Time Buyer)

[firsttimebuyergreg]

Hi all - first, wanted to say thank you to those participating and contributing on these forums - I've been doing research and have found this forum to be an invaluable resource. By way of background, I'm a first time buyer of a diamond (for an engagement ring), and have a general question regarding GIA Grades vs HCA Tool.

I've found a stone at what seems to be a reasonable market price with the following GIA Grades:
Carat Weight: 1.51
Color: E
Clarity: VS2
Cut: Excellent
Polish: Excellent
Symmetry: Excellent
Fluorescence: None
Depth %: 61.3
Table %: 60
Crown Angle: 33.0
Pavilion Angle: 41.8

Running the 4 measurement metrics through the HCA Tool provides the following marks:
Light Return: Fair
Fire: Fair
Scintillation: Fair
Spread: Vey Good
Total Visual Performance: 6.0 - Fair
________________________________________________

So based on the advice of many on this forum, and in general, it looks like I should completely rule out this diamond based on HCA, despite the incredibly strong GIA Grading. I'm torn only because I've found a solid price per carat on this gem...

So my general question is - how much stock do I put in this HCA Tool report? Is 6.0 so poor, that this should absolutely be ruled out, despite the strong GIA Grading? Any thoughts on this, or other appraisal I should be looking at, would be much appreciated.

Thanks again in advance!

Best,
Greg

 

[Texas Leaguer]

Hi all - first, wanted to say thank you to those participating and contributing on these forums - I've been doing research and have found this forum to be an invaluable resource. By way of background, I'm a first time buyer of a diamond (for an engagement ring), and have a general question regarding GIA Grades vs HCA Tool.

I've found a stone at what seems to be a reasonable market price with the following GIA Grades:
Carat Weight: 1.51
Color: E
Clarity: VS2
Cut: Excellent
Polish: Excellent
Symmetry: Excellent
Fluorescence: None
Depth %: 61.3
Table %: 60
Crown Angle: 33.0
Pavilion Angle: 41.8

Running the 4 measurement metrics through the HCA Tool provides the following marks:
Light Return: Fair
Fire: Fair
Scintillation: Fair
Spread: Vey Good
Total Visual Performance: 6.0 - Fair
________________________________________________

So based on the advice of many on this forum, and in general, it looks like I should completely rule out this diamond based on HCA, despite the incredibly strong GIA Grading. I'm torn only because I've found a solid price per carat on this gem...

So my general question is - how much stock do I put in this HCA Tool report? Is 6.0 so poor, that this should absolutely be ruled out, despite the strong GIA Grading? Any thoughts on this, or other appraisal I should be looking at, would be much appreciated.

Thanks again in advance!

Best,
Greg

You don't necessarily need to rule it out if light performance is not your priority. This stone does get the top cut grade from GIA, but their top grade is overly broad. That's where the HCA tool comes in handy for weeding out some of the not so excellent GIA Excellents! You can compare this stone to others of the same color clarity and weight but with an HCA score of around 2 or less and see what is available. You might be surprised. Most folks here will tell you that you should not compromise much on cut quality because that's what puts the sizzle on the steak.

To put the GIA grade in a little perspective, it would likely be an AGS 2 or below (where 0 is ideal). When considering price and value, one way to look at it is to consider what the stone would have weighed and what would the market price have been had it been cut for maximum beauty. I would have fallen below the 1.50 ct magic mark and would have been priced lower. Therefore, it can seem like you have a solid price based upon the weight, but leaving the extra weight on was done for market reasons that came at the expense of performance.

 

[solgen]

The specs on that stone don't look like they'd lead to a well performing diamond.

 

[diamondseeker2006]

I would definitely rule that one out. You can do much better. I would rather have G or H color and a well cut diamond any day over an E color that is not well cut.

 

[JDDN]

Texas Leaguer put it very succinctly.

I think that with all the options available to you, you will be able to find a better looking diamond. It's unfortunate for the consumer that GIA's 3X is so very broad and that it includes not so great performing diamonds. You will need to be more discerning with a GIA stone, but beautiful ones can certainly be found. The other option is to look for an AGS 0 diamond.

Good luck to you!

 

[firsttimebuyergreg]

All - thank you very much for the responses and guidance, it is much appreciated! I believe I will pass on this stone, then, and keep looking...

Question on the HCA Tool -- https://www.pricescope.com/tools/hca

These are the 5 stats I have for a new stone I am looking at:
Depth %: 61.2%
Table %: 59%
Crown Angle: 33.5
Pavilion Angle: 41.2
Running these 4 - I get a Very Good across the board -- Cut Score of 2.9

However, when I replace Pavilion Angle metric with Pavilion Depth (43.5%) -- I get a Cut Score of 1.7 (I did not enter a Culet % as there is None)

I understand that the HCA tool prefers angles (as noted on the page) -- but I'm surprised by this large a variance in the score? Was curious as to why this might be?

Thank you again in advance for your wisdom!

Best,
Greg

 

[John P]

Pavilion Angle: 41.2
Running these 4 - I get a Very Good across the board -- Cut Score of 2.9

However, when I replace Pavilion Angle metric with Pavilion Depth (43.5%) -- I get a Cut Score of 1.7 (I did not enter a Culet % as there is None)

I understand that the HCA tool prefers angles (as noted on the page) -- but I'm surprised by this large a variance in the score? Was curious as to why this might be?

GIA round many of the numbers on their reports up or down. In this case both PA and PD are influenced. PA in 0.2 degree increments. PD in 0.5% increments.

* With no culet a 41.2 degree PA should correspond to a PD of 43.8%.- which GIA would round up to 44.0%.
* With no culet a 41.1 degree PA would correspond to a PD of 43.6%.- which GIA would round down to 43.5%.

In this case the actual PA average (an average of eight separate measurements) would seem to be 41.1 degrees, which becomes rounded up to 41.2 degrees by GIA. In that case the actual corresponding PD would be 43.6%, which becomes rounded down to 43.5%.

Hope that helps.