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Does HCA score matter to an AGS0 cut?

B

bqnbqn

Rough_Rock
Joined
Jun 12, 2014
Messages
17
This was briefly addressed in another thread but I wanted focus on just this issue. I have seen comments where folks say the HCA score does not apply to AGS0 cut diamonds while others swear not to consider stones with less than a 2.0 HCA score. The diamond I'm considering buying is a AGS 0 cut H&A but has an HCA score of 3.0. Would appreciate any further opinions on whether this score really makes a difference on this particular stone:

http://www.agslab.com/pdf_sync_reports/104071002017-PLDQR.PDF

Thanks for your feedback.
 
bqnbqn|1403611095|3699926 said:
This was briefly addressed in another thread but I wanted focus on just this issue. I have seen comments where folks say the HCA score does not apply to AGS0 cut diamonds while others swear not to consider stones with less than a 2.0 HCA score. The diamond I'm considering buying is a AGS 0 cut H&A but has an HCA score of 3.0. Would appreciate any further opinions on whether this score really makes a difference on this particular stone:

http://www.agslab.com/pdf_sync_reports/104071002017-PLDQR.PDF

Thanks for your feedback.
Click to expand...

Hi bq,

I believe the use of the HCA is actually valid for some AGS0 diamonds, case in point, this one, they won't all score <2. It's the case that some AGS0 are in fact hovering around borderline steep/deep angles such as this diamond, which can sometimes cause light leakage. Conversely, I don't assume that even with a diamond that scores between 1 and 2 right in the HCA sweet spot is going to automatically be a stunning stone, anymore than a stone scoring >2 is going to be a dud, there are other factors that can swing things either way and an image is absolutely essential for these diamonds so we don't dismiss potentially fantastic options for no good reason. I think the HCA is useful for consumers with AGS0 diamonds in some cases to alert them that some further evaluation might be useful, some might disagree and that's absolutely fine but I am noticing that there is the odd AGS0 diamond I wouldn't buy from the cut grade alone ( normally non branded) and I would absolutely insist on more info, but that's me.

This diamond has definite potential, personally I prefer an actual ASET or Idealscope image rather than a computer generated one from AGS that appears on the report, but having said that, the experts say these images are a good ' footprint' of the stone in question and thus very useful. For the money you are spending, I would personally request an actual ASET or Idealscope image to make absolutely sure there is not any or not much in the way of light leakage due to the angle combo, especially as this is going to be a very sizeable purchase. Do you have any hearts and arrows images as you mention the diamond is sold as a h&a cut? These are essential in order to determine if this diamond has the strict cut precision of its h&a patterning as it is sold as such. My gut feeling tells me this is probably a very well cut diamond indeed but it's not cut to the tight standards of the Superideal h&a branded diamonds we see here often. But it depends what you want, it's certainly going to be well cut, great colour, high clarity, but an actual image would be useful to see how well everything works together especially the angle combo, plus the depth is a little more than I personally prefer but that's not a deal breaker. Hearts and arrows images are a must if you want a stone that displays crisp and precise patterning and if that's important to you, the vendor should be able to supply these if this diamond is advertised as h&a.

I hope this is helpful!
 
Thanks for the reply. I have posted this stone on another topic but it quickly became a heated but cordial GIA vs. AGS grading discussion :) so I wanted to get back to the fundamental question I was interested in which is the relationship of a low HCA score to an AGS 0 cut stone. The vendor said they do not collect ASET images for round brilliant, only fancy stones. Is this common? Should I insist on an ASET image? It is from James Allen by the way. Here are the H&A images they have provided.

From the other thread, some folks have commented that it is indeed a well-cut stone. I am just curious about the possibility of a well-cut stone that has a so-so HCA score. Is that common?

_19474.jpg

_19475.jpg

_19476.jpg
 
bqnbqn|1403618642|3699977 said:
Thanks for the reply. I have posted this stone on another topic but it quickly became a heated but cordial GIA vs. AGS grading discussion :) :lol: so I wanted to get back to the fundamental question I was interested in which is the relationship of a low HCA score to an AGS 0 cut stone. The vendor said they do not collect ASET images for round brilliant, only fancy stones. Is this common? Should I insist on an ASET image? It is from James Allen by the way. Here are the H&A images they have provided.

From the other thread, some folks have commented that it is indeed a well-cut stone. I am just curious about the possibility of a well-cut stone that has a so-so HCA score. Is that common?
Click to expand...

LOL! I was away from the boards mostly last week so I must have missed that one, but it happens time and time again! :lol: As the diamond is from JA and we have the images we need, that's fine. The images are excellent, I can nit pick a couple of things with the optical symmetry patterning but it's a very fine stone indeed and the patterning is also very precise, it's showing what I hoped it would and the results are good!

I have seen quite a few well cut diamonds with a so so HCA score yes. The HCA is working from very limited information, it can't see the stone and allow for aspects of the diamond's proportioning, faceting and overall cut precision that might improve how the critical angles work that mitigates any light leakage or other undesirable effects etc. The HCA also penalizes steeper pavilion angles on their own as well as coupled with steeper crowns which can give a lower score to a very nice diamond, as in this case. Things have moved on a lot in the almost 10 years I have been here, in my early days we didn't have all that we use routinely to evaluate diamonds that trump the HCA scores or even the knowledge we now use all the time, but it is my belief the HCA is still relevant used properly as an rejection tool.

PS - curiosity made me go back and check out that thread you mentioned, it was fantastic and very useful!
 
 
bqnbqn|1403618642|3699977 said:
The vendor said they do not collect ASET images for round brilliant, only fancy stones. Is this common? Should I insist on an ASET image?
Click to expand...

This is common.
 
To my amateur eye it looks like that second, IdealScope image has a small amount of light leakage (white light) at the edges of the middle ring, but the red (light return) is still pretty good so I think it will still look nice :)
 
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