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New HCA update!

Discussion in 'RockyTalky' started by FearlessSmile, Apr 16, 2019.

  1. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 16, 2019
    New HCA update is pretty nice! Anyone used it yet?
     
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  2. Johnbt
    Shiny_Rock

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    by Johnbt » Apr 16, 2019
    I just did. When I used the AGS number I got a 0.9, but when I entered the numbers from the WF site myself I got the same 1.0 I got a year ago. I don't know if it's the program rounding the table to 56 from 55.9 or what. I don't think it's the rounding from 1.514 carats to 1.51. Doesn't matter, the ring is still beautiful.

    Hey, we're back at the beach a year later and I haven't lost her ring this time. Yet. I have until Friday though, so keep your fingers crossed. Everything should be okay this year... she won't take it off. =)2
     
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  3. OoohShiny
    Ideal_Rock

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    by OoohShiny » Apr 16, 2019
    I think it should be really useful for illustrating the benefits and trade-offs of the different options - such as 60/60, shallower cuts, high-crown cuts, etc. - and also show how poor cuts look smaller! :)
     
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  4. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 16, 2019
    Yeah definitely, although the diamond I returned a few weeks ago was 34.5 crown, 41.4 pavilion, 61.8 depth with 58% table, think it came just under 5 on HCA score but still showed as average for size (the beta tool) was expecting it to say smaller.
     
    


    


  5. sledge
    Ideal_Rock

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    by sledge » Apr 16, 2019
    I've toyed with this version of the HCA for a little bit.

    I think the "looks like" portion is pretty cool personally, as it illustrates different personalities of stones and how they affect the spread/size of the stone. For instance, a stone with a large table and shallow crown (and consequently less depth) will have a larger spread. A stone with a smaller table and steeper crown will not have as much of a spread.

    People get hung up on carat weight too much IMO. Much of the weight is "hidden" in depth, so when the proportions aren't right it affects if a diamond looks it weight, or is small or large for its weight. I believe that was what Garry and Andrey was trying to show.

    Even when a stone is cut to ideal proportions, the various combinations can have this effect. When I was looking at a stone for my fiancee I was looking at a 0.91 WF and 0.867 BGD stone. Both were cut very well and had passing ASET, IS and H&A imaging. Yet because of proportions the 0.867 actually had a little larger spread than the 0.91 stone.

    So please be careful and not assume that a stone that ranks as average, large or small is automatically good or bad in light return. While I would agree that size and light performance correlate with each other to a certain degree, they can also be independent.

    In the case of your stone, I am sure the HCA penalized it heavily for the 41.4 pavilion. In an ideal world, a 34 crown pairs nicely with a 40.9 or maybe 41 pavilion (if faceting is very precise & tight). At 41.2 things go wonky even if you get a complimentary crown angle. In your case, you had a crown and pavilion that wasn't complimentary to each other PLUS the pavilion was above 41.2. And truthfully, given the fact that GIA rounds, some of the pavilion mains were probably > 41.4. IMO, that was a good fish to cut loose as there are plenty more gorgeous ones in the sea.
     
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  6. Rockdiamond
    Ideal_Rock
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    by Rockdiamond » Apr 16, 2019
    I love the new addition! Kudos to Garry!
    Part of the reason why is this
    After participating here for many years, I can totally understand why people feel like this....but in fact, a well-cut 60/60 used to spread 6.5mm
    The GIA EX cut grade put an end to all that- and now carat stones rarely break 6.4mm.
    Sellers of "Ideal Cuts' will say such stones appear larger due to girdle to girdle brilliance.....and if we're comparing two 6.3mm stones, that may be true.
    But a well cut 60/60 spreading 6.5 will appear larger than a super ideal of 6.3mm.
    But OoohShiny is also correct given the huge amount of "steep deep" stones out there today.
     
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  7. OoohShiny
    Ideal_Rock

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    by OoohShiny » Apr 16, 2019
    I am kind of wondering how the tool works with regards to the Looks Like aspect.

    Does the tool just take the mean or median of a large sample of stones of a given weight, in order to then base an assessment of an individual size against that mean/median size?

    Or does it also include some assessment of likely edge-to-edge brightness (or lack thereof), perhaps using the GIA/AGS ASET image tables for the different crown/pavilion combinations, and then base the Looks Like grade against a SuperIdeal or good 60/60 or the 'best' ASET images?

    Or a combination of the two?

    Or something completely different?? :???: :lol:

    I appreciate it is a patented tool and such details may well be a proprietary secret, though ;-) lol
     
    Last edited: Apr 16, 2019
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  8. OoohShiny
    Ideal_Rock

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    by OoohShiny » Apr 16, 2019
    Wait! I found some science :D

    The blog has the top level stuff:
    https://www.pricescope.com/blog/looks-like-the-new-addition-to-hca

    and links through to the science :))
    https://www.pricescope.com/wiki/hca-looks-like-apparent-diamond-size


    It's too late in the evening to look at the maths section :lol: but I am intrigued by the peripheral brightness measurement at different tilt angles, as shown here:

    [​IMG]

    Just thinking out loud, but if it's possible to measure digital pixel brightness, does that mean it's also possible to measure maximum and minimum brightness? And therefore measure contrast ratios? Not just round the edges but across the whole stone? In order to quantify perceived brightness of the brightest areas and weed out stones that are just sort of dull grey and boring, instead of being full of life?

    Or is that exactly what @Serg's work has been doing?


    Either way, I think the fact the graph suggests it's possible at tilt angles is really potentially useful - I feel like I bring it up a lot, but for me, ASET limited to head-on only images limits its usefulness in terms of understanding how a stone performs during movement (i.e. in more 'real life' situations), especially for fancies such as stepcuts, which really do need assessment at all angles to ensure they are not a stinker, lol.

    If analysis and comparison was possible at different angles, not just in terms of ASET performance but also the brightness/contrast performance, that could illustrate/evidence stones that really perform well and aren't just cut for one-angle (face-on) performance and hitting AGS targets, i.e. that are cut to perform well in motion?

    @diagem mentioned in a recent Instagram posting about how he and/or his team had cut a stone deliberately to perform well in motion (or at angles other than face-on - I can't remember the exact wording now) so although I know he is not a man that lives and dies by measured performance, instead preferring beauty, perhaps an assessment tool that worked at a variety of angles would show his skill?


    I don't know... I'm probably over-tired, under-caffeinated, and just letting my train of thought derail slowly in a remote siding far off the actual beaten track... :lol:
     
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  9. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 16, 2019
    Here is a concise description that should answer your questions (and everyone elses).
    https://www.pricescope.com/wiki/hca-looks-like-apparent-diamond-size
    The algorithm uses mm spread PLUS edge leakage.
     
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  10. OoohShiny
    Ideal_Rock

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    by OoohShiny » Apr 16, 2019
    Thanks Garry! :))

    I need some sleep to get my head entirely around it, lol, but will do so tomorrow :)

    You will see I went on to waffle some more, though, but off on a tangent after posting initially... :D lol
     
    


    


  11. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 16, 2019
    I will have a crack at some of your comments OS
     
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  12. headlight
    Brilliant_Rock

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    by headlight » Apr 16, 2019
    I'm so sorry... I got so excited about the new HCA that I started my own thread before I saw this one. Irregardless, it was very kind to my diamond :)
     
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  13. angeljosephy
    Rough_Rock

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    by angeljosephy » Apr 16, 2019
    Just checked my stone and it says "Looks Like size BETA". What does Beta even mean?:confused:
     
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  14. psadmin
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    by psadmin » Apr 16, 2019
    The "Beta" means that the New "Looks Like" addition to the HCA still being tweaked.
     
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  15. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 16, 2019
    "In software development, a beta test is the second phase of software testing in which a sampling of the intended audience tries the product out."
    You are a beta tester AJ :)
    And no prob's Headlight
     
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  16. gm89uk
    Brilliant_Rock

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    by gm89uk » Apr 17, 2019
    @Garry H (Cut Nut)
    Just a small correction
    Spread = (D/(6.44))3 – C
    To
    Spread = (D/(6.44))^3 – C

    Looks great. Like the average option. I like the formulae
     
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  17. the_mother_thing
    Ideal_Rock

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    by the_mother_thing » Apr 17, 2019
    When I plugged my AGS report # in, the result was 1.2; when I entered the full numbers directly from WF, it returned 1.1.
    7A81708F-7DDB-402F-A5D4-CAFF66DFCC3A.jpeg
    E7CB3A6A-916C-4AA5-920E-3DF45741BC51.jpeg

    I like how - when you click the ‘For more info’ link under the looks-like diamond image - it explains the different spreads! That should prove useful for novices. FTR, my girdle per AGS is thin-sl thick.
    2C81CDE7-3009-4A0C-BEE6-70D92839409B.jpeg
     
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  18. psadmin
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    by psadmin » Apr 17, 2019
    Hi @the_mother_thing

    Would you mind sharing the AGS Cer ID with me? It will help me understand the difference.

    If you prefer to keep it private just use the contact us and it should get to me.

    Here is a link for your convenience. https://www.pricescope.com/contact

    Thank you
     
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  19. Johnbt
    Shiny_Rock

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    by Johnbt » Apr 17, 2019
    Fwiw, here's my AGS# from post #2 - the 0.9 vs 1.0 HCA

    104097975020
     
  20. John Pollard
    Ideal_Rock
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    by John Pollard » Apr 17, 2019
    Congrats on the update. I enjoy reading the reactions.

    @Rockdiamond hello. I get the spirit of your post. In the interest of fact-checking can you link me to any 1.00 ct RB only spreading 6.3mm yet graded AGS Ideal? Never mind "super ideal". Even generic Ideal should not be possible.

    Thank you,
     
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  21. psadmin
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    by psadmin » Apr 17, 2019

    You are correct and I fixed it.

    Thank you!
     
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  22. psadmin
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    by psadmin » Apr 17, 2019

    That was perfectly helpful. I believe I know what it is, but I want to make sure.
     
  23. Rockdiamond
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    by Rockdiamond » Apr 17, 2019
    Hi John
    I hope you're well and get to stay home for the holidays:)
    Re-reading my post- I never wrote that AGS Ideal cut stones don't break 6.3mm.
    A quick search on Rapnet turns up a minuscule sampling of AGS Ideal Cut ( 0 Polish/Symmetry/Cut)
    and indeed, all of the 24 stones ( search parameters 1.00ct/AGS/no color/clarity restrictions) broke 6.3mm- ranging from 6.34 to 6.52
    The same search for GIA graded stones yields 16638 diamonds- many are smaller than 6.3mm
    I don't know that we can find metrics but my gut feeling is that spread on well cut stones was far better on average before the GIA introduced the cut grade.
    I think we both agree that adding the "Look Like Size" data on HCA is a big plus.
     
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  24. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 17, 2019
    The difference is based on the symmetry. I did not yet announce it, but please to see that folk have noticed.
    I added a symmetry bonus / penalty to HCA because it is important for the Looks Like estimation
     
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  25. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 17, 2019
    Capture.JPG
     
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  26. Rockdiamond
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    by Rockdiamond » Apr 17, 2019
    @Garry H (Cut Nut)
    Kudos on the improvement!!
    We're in total agreement.
    There are so many horribly cut stones gaining a GIA EX cut grade- and in virtually all cases, they are deep stones, as opposed to "spready" ones. The new feature will really assist shoppers
     
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  27. the_mother_thing
    Ideal_Rock

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    by the_mother_thing » Apr 17, 2019
    My AGS # is 104097609018
     
  28. Dancing Fire
    Super_Ideal_Rock

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    by Dancing Fire » Apr 17, 2019
    The bottom half is too deep at 44%. :knockout:. I'd prefer a 1ct at 6.45mm
     
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  29. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 17, 2019
    DF it is wrong to use %'s. angles are what light performs too.
    For example is a crown angle is 2 degrees lower than Tolkowsky then 44% is optimal.
    And if a stone has a small culet then that can bump your 44% up by 0.2 degrees from 41.3 to 41.5.
     
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  30. Dancing Fire
    Super_Ideal_Rock

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    by Dancing Fire » Apr 17, 2019
    Aren't most MRB pointed?
     
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