Do ASET/IS images make HCA unnecessary?
- Thread starter skypie
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This is how I feel as well!
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I'm fairly confident reading/commenting on stepcut ASETs (which is hopefully not misplaced - please someone tell me if it is!! 
) because they are usually considered side-by-side with videos, and stepcuts in general seem to be more about the 'flavour' of the performance than hitting a set light-performance-based target (e.g. AGS000).
MRBs I am far from confident, though because the angles need to be exactly right and there are nuances such as painting and digging, which I'm not yet good at spotting. I also can't really tell from an ASET what the angles might be / if it's overexposed / etc.
I therefore (personally) rely on HCA above ASETs - in that if the angles work on the HCA, the ASET is backup to check the cut accuracy of the major facets.
) because they are usually considered side-by-side with videos, and stepcuts in general seem to be more about the 'flavour' of the performance than hitting a set light-performance-based target (e.g. AGS000).MRBs I am far from confident, though
because the angles need to be exactly right and there are nuances such as painting and digging, which I'm not yet good at spotting. I also can't really tell from an ASET what the angles might be / if it's overexposed / etc.I therefore (personally) rely on HCA above ASETs - in that if the angles work on the HCA, the ASET is backup to check the cut accuracy of the major facets.
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yes and no.
IS/ASET are not good at showing obstruction issues.
HCA also does some sanity checks on potential girdle issues and other things.
But yes in general real images trump HCA.
It is a good sanity check to the images.
There are combinations that score 2.5 or even higher that I would buy with good images.
There are some combinations that when combined with the right minor facets are just kicken but with others not so much.
HCA gives both the same score.
I have done this enough that I run a hca like process in my head on most combinations rather than using the actual hca.
IS/ASET are not good at showing obstruction issues.
HCA also does some sanity checks on potential girdle issues and other things.
But yes in general real images trump HCA.
It is a good sanity check to the images.
There are combinations that score 2.5 or even higher that I would buy with good images.
There are some combinations that when combined with the right minor facets are just kicken but with others not so much.
HCA gives both the same score.
I have done this enough that I run a hca like process in my head on most combinations rather than using the actual hca.
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Maybe I look at things differently, but I see all the images and HCA as tools we utilize in an effort to determine actual light performance of a stone. Keyword, actual.
IMO, real images (not computer generated ones) provide the insight to actual diamond performance. There are nuances -- back lighting, tilting, etc that can make them hard to accurately read.
On the flip side, the HCA is easier to input and have less (obvious) nuances to the end user. Enter data and assuming no typos were made, it kicks out a number. It's kind of a pass/fail process which is inherently easy to grasp & understand. But here's my rub -- it uses a proprietary set of calculations and assumptions using data that is averaged/rounded by a 3rd party entity to provide a result.
So it's ability to predict is limited by what's entered and the software coding. We know there are 8 actual crown & pavilion values that either get averaged (AGS) or averaged & rounded (GIA) to a single value on each respective report.
I'm not privy to the design/coding of the HCA software, but I'm guessing one of two things happens. If you are analyzing a stone with entered 35 crown and 40.6 pavilion then the software either sees all 8 values as a static 35/40.6 combo or it makes an assumption that because of real world rounding & averaging there must be some (assumed) % of variation. So mathematically the program would then start assigning random combinations like 35.3/40.4, 35.1/40.6, 34.8/40.8, etc to build a computer generated model based on realism.
I'm going to refrain from going further into my thought detail, but I think this illustrates how you are taking assumed data, making a few more assumptions and kicking out a result. At the end of the day, I think it's close but it's really an approximation and consequently (in my head) not as accurate as real image results. But I think this was the intent of the software -- to give us an approximation, not an exactimation. This is no secret, as the HCA tools page encourages IS image evaluation to confirm HCA results and provides ranges for various conditions:
But as @Karl_K pointed out, it also addresses a different line of thinking and observations that everyone may not think of if it didn't exist. As such I think it's a good tool that provides value, and compliments real images.
Although I'm a newbie compared to Karl, I go through a similar HCA thought process in my head about what angles are complimentary, how depth plays into it, etc so I'm rarely caught off guard by a particular HCA score.
Heaven forbid I ever get the toys and software that Karl has, as I could really analyze the hell out of stuff that would bore most of you. LOL
IMO, real images (not computer generated ones) provide the insight to actual diamond performance. There are nuances -- back lighting, tilting, etc that can make them hard to accurately read.
On the flip side, the HCA is easier to input and have less (obvious) nuances to the end user. Enter data and assuming no typos were made, it kicks out a number. It's kind of a pass/fail process which is inherently easy to grasp & understand. But here's my rub -- it uses a proprietary set of calculations and assumptions using data that is averaged/rounded by a 3rd party entity to provide a result.
So it's ability to predict is limited by what's entered and the software coding. We know there are 8 actual crown & pavilion values that either get averaged (AGS) or averaged & rounded (GIA) to a single value on each respective report.
I'm not privy to the design/coding of the HCA software, but I'm guessing one of two things happens. If you are analyzing a stone with entered 35 crown and 40.6 pavilion then the software either sees all 8 values as a static 35/40.6 combo or it makes an assumption that because of real world rounding & averaging there must be some (assumed) % of variation. So mathematically the program would then start assigning random combinations like 35.3/40.4, 35.1/40.6, 34.8/40.8, etc to build a computer generated model based on realism.
I'm going to refrain from going further into my thought detail, but I think this illustrates how you are taking assumed data, making a few more assumptions and kicking out a result. At the end of the day, I think it's close but it's really an approximation and consequently (in my head) not as accurate as real image results. But I think this was the intent of the software -- to give us an approximation, not an exactimation. This is no secret, as the HCA tools page encourages IS image evaluation to confirm HCA results and provides ranges for various conditions:
But as @Karl_K pointed out, it also addresses a different line of thinking and observations that everyone may not think of if it didn't exist. As such I think it's a good tool that provides value, and compliments real images.
Although I'm a newbie compared to Karl, I go through a similar HCA thought process in my head about what angles are complimentary, how depth plays into it, etc so I'm rarely caught off guard by a particular HCA score.
Heaven forbid I ever get the toys and software that Karl has, as I could really analyze the hell out of stuff that would bore most of you. LOL
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