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question about the "cut quality search"

Discussion in 'RockyTalky' started by Go Blue 99, Aug 28, 2006.

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  1. Go Blue 99
    Rough_Rock

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    by Go Blue 99 » Aug 28, 2006
    There is an "AGS" column in the search results. A lot of GIA graded diamonds have "0" under the AGS column. Does this mean they would definitely qualify for an AGS 0 if AGS had graded it? If so, would you be just as happy with an GIA as an AGS diamond?

    Also, someone last week posted about a diamond that had a 1.9 HCA score. Another poster used % instead of angles, and said the HCA was a 1.6 instead. Should I run % for every stone I am considering?

    thanks for the help!
     
    


    


  2. Bluehammer
    Shiny_Rock

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    by Bluehammer » Aug 28, 2006
    I do not know if the GIA would qualify for the AGS0 since they are two different labs. There have been studies done where a single stone was graded slightly different depending on the lab. Howevere, this study seemed to indicate diff. in color and clarity, not ideal cut.

    You could run the HCA on the GIA stone to see if it falls within the category for measurement. However, the new AGS report takes into account light performance.

    I think a GIA Excellent cut (new report) would be comparable to AGS0. You should be happy with either stone. You do not have to buy an AGS only diamond.

    My understanding is that using angles on the HCA would be more precise than percentages. I do not know the engine behind the HCA, but I do recall past posts that indicate angles are a more precise measurement. Keep in mind the HCA is a tool to weed out potential bad stones. If you get caught up in pure numbers, you could miss out on a great stone.

    Use the numbers to point you the right way, use your eyes to pick the stone.
     
  3. Regular Guy
    Ideal_Rock

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    by Regular Guy » Aug 28, 2006
    Unfortunately, there''d be no basis for that without direct examination, and no set of numbers...what that 0 will be based on, will give you that. Interestingly, I saw a "1" recently where the AGS cert was new, and though I saw no basis for it then, your question anew raises what it''s about. I''m guessing, it''s based on the old AGS formula only, but perhaps the admin will review.


    Few things are more clear here...but % is inferior to angle, always. Read the detail on the HCA utility to confirm.
     
  4. belle
    Super_Ideal_Rock

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    by belle » Aug 28, 2006
    ''definitely''? no. only diamonds graded by ags that are given the ''0'' designation are definitely ags0. based on angles, there are diamonds that would qulaify them as ags0 candidates but unless they are given the grade by ags you can''t say they would ''definitely'' be ags0.
    there are certain angle combinations that are more likely to be ags0 without question though. i''m not sure how the search tool is set up and i haven''t checked it. if only diamonds that are listed with angles that are well within the ags0 parameters are listed (no boderline angles) i would have more confindence that a non-ags graded diamond would have received the designation.

    i have one and i am.[​IMG] absolutely.

    angles are more accurate. percentages *may* give you a better score but it won''t change the look of the diamond. the bottom line is, you can''t choose a diamond using hca alone. once you get under 2.0 with the score, you have eliminated 95% of poor performing diamonds. once you hit that level, you need to either see the diamonds side by side or choose based on more information.
     
    


    


  5. Ellen
    Super_Ideal_Rock

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    by Ellen » Aug 28, 2006
    Blue pretty much answered everything. I bought a beautiful GIA stone.

    The only thing I would recommend with a GIA stone is getting a sarin to see the real numbers, as they do round. It might not make that much difference on some stones, but those that border certain angles, you''d want to know.
     
  6. Regular Guy
    Ideal_Rock

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    by Regular Guy » Aug 28, 2006
    Inclusive of the new AGS protocols...it would be nice if this calculation, including not only 0...but the 1, 2, etc, when reviewing for HCA, were available.

    (Edited to add...) I probably earlier thought the old AGS formula were employed, because I believe it has been and probably is still the case that, in the big db here (search all), when you check AGS0 there, you are I think only checking for where the cert has text imbedded that says "AGS0" on it, and this has been tied to the old formula. But then, this is different than the search by cut db, where crown & pavilion data has already been extracted, so there is at least the potential to do more, I would think.
     
  7. devientdrow
    Brilliant_Rock

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    by devientdrow » Aug 28, 2006
    The other posts are really informative and there are lots of other threads recently discussing differences between the AGO0 and GIA Excellent. My stone is a GIA, and i''m VERY happy with it. I personally couldn''t tell that much of a difference between the AGS0 stone I was looking at and the GIA. I chose the GIA because it was a little larger. .83ct as opposed to .73ct. That doesn''t mean some other people won''t notice. However I am very happy with my stone. It''s gorgeous. It has "ideal" proportions and scores a 1.7% on the HCA.
     
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