Am I using the HCA incorrectly?

[bg23eagle]

Hi all:

I'm a long-time lurker here and this is my first post. I've learned so much from this site and I'm getting ready to buy my first diamond! I am inputting the following inputs into HCA tool and I'm receiving an HCA score of 2.3, but the search results page on the site lists an HCA of 2.0. Am I rounding the inputs differently than the search engine would?

Depth %: 62.0%
Table %: 57.0%
Crown angle: 35.27 [I inputted 35.3]
Pavilion angle: 40.75 [I inputted 40.8]

Thanks very much for your help!

 

[Anonymous6]

If anything, I'd think the depth and table are rounded, as they end in a nicely placed .0

If not, then 2.3 is still a great score on HCA and to my understanding, HCA score is more of a weed out process (I weed out anything over 3.5 and anything under that is worth looking into for me)

I'm pretty sure most people couldn't tell the difference from many stones that score "poorly" on the HCA with stones that score 1-2 on the HCA

 

[slg47]

it's possible that the search page doesn't round? (this is just a guess, if you round down you get HCA = 1.6)

HCA is a blunt weeding tool that is useful but has limitations. An IS image of this stone will tell more.

Anon, have you seen this article? to me there is a very clear difference in appearance between the HCA excellent and the HCA fair performers. https://www.pricescope.com/journal/laboratory_cut_grades_what_report_doesn%E2%80%99t_show
This video also illustrates the importance of cut quality, which is what HCA tries to assess http://vimeo.com/2556364

 

[bg23eagle]

Thank you both for your reply!

 

[Amys Bling]

it's possible that the search page doesn't round? (this is just a guess, if you round down you get HCA = 1.6)

HCA is a blunt weeding tool that is useful but has limitations. An IS image of this stone will tell more.

Anon, have you seen this article? to me there is a very clear difference in appearance between the HCA excellent and the HCA fair performers. https://www.pricescope.com/journal/laboratory_cut_grades_what_report_doesn%E2%80%99t_show
This video also illustrates the importance of cut quality, which is what HCA tries to assess http://vimeo.com/2556364

ditto.. I think that the cut component of the 4 C's is one that is often overlooked. If you are looking for an excellent cut stone, he HCA score should be between 0-2. 2-4 is considered very good- a 2.5 versus a 3.5, will not determine which one is better. The tool is used to cut stones into more defined cut grades.. If you are aiming for excellent, anything 0-2 is worth further consideration.

as for the numbers you ran- maybe the HCA score on the search engine split the difference between the 2.3 you go from rounding up- and the 1.6 slg got from rounding down!

 

[stone-cold11]

The PS search engine probably uses the grading report's number. The numbers you are using is probably from a sarin's scan of the stone by the vendor.

 

[yssie]

If anything, I'd think the depth and table are rounded, as they end in a nicely placed .0

If not, then 2.3 is still a great score on HCA and to my understanding, HCA score is more of a weed out process (I weed out anything over 3.5 and anything under that is worth looking into for me)

I'm pretty sure most people couldn't tell the difference from many stones that score "poorly" on the HCA with stones that score 1-2 on the HCA

I am with you re. under ~3.5.

The HCA is meant only for the modern 57/58f RB - AVRs, OECs/OMCs, etc. do not fall into this category.. and HCA does not consider lgf as variable input

It is an excellent tool, one of many, and should not be used to the exclusion of all else.