Questions about Hollaway Cut Advisor (HCA) Score

[kthan]

I have one question about HCA score.
I do learn that HCA score is just one of the tool to evaluate the quality of a stone.
We do not know the performance of the stone in polish, symmetry, etc.
However, it seems to be useful to know how well cut a stone is.
Isn''t this better indicator about the quality of cut than AGS cut grade?
(I am a newbie, so pleaes correct me if I am wrong).

Also, I found that, in the same range (ex: HCA 0-2, ,2-4...), we cannot tell
which stone is better performer. But, how about the two stones (HCA 1.0 and HCA 2.4)?
Can I tell HCA 1.0 stone is better than 2.4 for sure?

If i can only access the paper data (Certificate and Sarin Report), can I use HCA as an indicator
to find if a stone seems to be an ideal cut + better performer (in other categories, like polish
and symmetry)?

 

[aljdewey]

Date: 9/23/2005 3:33:04 PM
Author:kthan
I have one question about HCA score.
I do learn that HCA score is just one of the tool to evaluate the quality of a stone.
We do not know the performance of the stone in polish, symmetry, etc.
However, it seems to be useful to know how well cut a stone is.
Isn''t this better indicator about the quality of cut than AGS cut grade?
(I am a newbie, so pleaes correct me if I am wrong).

Also, I found that, in the same range (ex: HCA 0-2, ,2-4...), we cannot tell
which stone is better performer. But, how about the two stones (HCA 1.0 and HCA 2.4)?
Can I tell HCA 1.0 stone is better than 2.4 for sure?

No, you can''t. The HCA doesn''t tell "which stone is better". It''s a predictive tool meant to help identify which diamonds have the best chance of being strong performers.

It''s not designed to say "this 1.0 stone is better than this 2.4 stone". In fact, in person the 1.0 may look nicer to your eyes or worse....the HCA cannot factor in personal preference.

 

[kthan]

Thanks for information.

But, if I cannot see two stones in person, or if I cannot access the image(s) of a stone,
all I can do (to me) is to check the performance of the certificate (AGS cut grade, GIA polish/symmetry, and HCA score).

When I purchase a stone, I definitely need to have the stone(s) appraised before final decision.
But, I cannot send every possible candidates to an appraisal. In order to narrow them down,
I need above data and predict which one(s) might be better than others. Once a stone has
been fully (or even partially) analyzed with images(s)/test results, it should not be a problem.
But, if all data is just certificate and Sarin, would it be logical to eliminate a low Score HCA
stone(s) ?

For example, I found some possible stones. All are ideal cut (AGS 0) and EX/EX polish/symmetry on paper.
If I can access more data like idealscope image/H&A image I can know the permance of a stone. But, if only
the cert & sarin were given, and HCA turns out 2.6, maybe I need to remove the stone from the list.

 

[Garry H (Cut Nut)]

I would not rule our VG Pol and Sym, as that will braoden your list. but yes - HCA is designed to be used to reject stones over 2.0

 

[aljdewey]

Date: 9/23/2005 4:11:13 PM
Author: kthan
Thanks for information.

But, if I cannot see two stones in person, or if I cannot access the image(s) of a stone,
all I can do (to me) is to check the performance of the certificate (AGS cut grade, GIA polish/symmetry, and HCA score).

When I purchase a stone, I definitely need to have the stone(s) appraised before final decision.
But, I cannot send every possible candidates to an appraisal. In order to narrow them down,
I need above data and predict which one(s) might be better than others. Once a stone has
been fully (or even partially) analyzed with images(s)/test results, it should not be a problem.
But, if all data is just certificate and Sarin, would it be logical to eliminate a low Score HCA
stone(s) <not within the same 0-2 scale, but different scale 0-2 and 2-4>?

For example, I found some possible stones. All are ideal cut (AGS 0) and EX/EX polish/symmetry on paper.
If I can access more data like idealscope image/H&A image I can know the permance of a stone. But, if only
the cert & sarin were given, and HCA turns out 2.6, maybe I need to remove the stone from the list.

Narrowing the list down is exactly what the HCA is intended to do.

It''s true that there isn''t unlimited budget to send every stone for comparison, so many weed out the list by eliminating stones over 2.0 on the HCA.

It''s a rejection tool, not a selection tool.