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Best light return? Excellent symmetry or ideal cut?

Discussion in 'RockyTalky' started by gulliverseyes, Jan 23, 2008.

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  1. gulliverseyes
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    by gulliverseyes » Jan 23, 2008
    My understanding is that cut covers the over all angles (crown and pavilion) and symmetry is how the individual cuts make an even shape (perfect hearts and arrows, for example). Is this correct, and if so, which has the most influence on the best light return.

    Thanks in advance.
     
  2. nolimits
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    by nolimits » Jan 23, 2008
    Read this article: http://diamonds.pricescope.com/symm.asp

    And note the following....
    "The diamond images we have used in this tutorial are mostly symmetrical. But in the real world very few diamonds are perfectly symmetrical, but symmetry is less important to the overall beauty of a diamond than the critical facet proportions. You may never notice any difference between diamonds with Ideal, Excellent Very Good or even some Good symmetry diamonds."

    That being said, you can have an ideal cut stone without perfect symmetry. [​IMG]
     
  3. gulliverseyes
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    by gulliverseyes » Jan 23, 2008
    Very interesting, sounds like cut is most important for light return, but many prefer the hearts and arrows...

    "During the GIA’s 70,000 observation study, diamonds with ‘Good’ symmetry, but proportions that would have qualified them for the top category, were generally not preferred by both trade & consumers survey participants."

    Perhaps the hearts and arrows shapes are over rated...

    "When polishing a rough diamond the aim is to cut the heaviest, most valuable diamond possible. This often means polishing a diamond with imperfect symmetry to avoid inclusions or just to achieve a "magic weight" (like 1.00ct). The polished diamond may be slightly off round, have variations in girdle thickness, tilting of the table, and off centering the table or the culet etc. Contrary to popular belief, symmetry defects in a diamond are often the result of a highly skilled cutter, rather than an indication of poor skills."
     
  4. JohnQuixote
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    by JohnQuixote » Jan 23, 2008
    The Symmetry grade on a lab report has to do with external facet shape, meet points and ''twist.'' It is independent from the diamond''s cut precision, or optical symmetry (H&A).

    Here is discussion about the history and importance of H&A.
    You can search and find many threads.

    One aspect good optical symmetry brings about is contrast (AGS) or pattern (GIA). We''re learning more about how optical symmetry influences performance - in all shapes, not just round - as we learn more about scintillation.

    As recently as 2004 this area was a mystery. Now the AGS and Sergey Sivovolenko are both engaged in further studies. Here is one cut geek thread, pursuant to an AGSL presentation last June.
     
  5. strmrdr
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  6. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 23, 2008
    For the normal human beings who do not wear H&A''s reflectors as spectacles, there has never been any proof that extreme H&A''s grade symmetry is any better than very nice optical symmetry.
    The point is where is the point that humans can see the difference?
    It will depend on your eye sight, the size of the diamond, the type of optical distortion etc
     
  7. JohnQuixote
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    by JohnQuixote » Jan 23, 2008
    At some point (SI, VS, VVS, IF) diamonds become eye-clean for anyone. Where is that point? It depends on eyesight, lighting, the specific diamond, the strictness of the person pronouncing the clarity grade, etc. There has never been any proof that extreme clarity is any better than very nice clarity...but some people like mind clean.

    Same argument for color, really. Do you 'need' D? Can you 'see' D? Maybe, maybe not. For most people DEF look the same, but again it depends on your eyesight, the lighting, the size of the diamond, the strictness of the grading pronouncement, etc.

    All extremes of rarity (color/clarity) and quality (cut precision/craftsmanship/light performance) cost. You will pay more for D, VVS and near-Tolk H&A than for near-colorless, SI and VG. None of those qualities are a requirement for diamond beauty (though cut arguably helps the others more) but they are all cool benchmarks. For every person there is the right balance and blend of qualities.
     
  8. aljdewey
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    by aljdewey » Jan 23, 2008
    1. On the grading report
    2. In the wallet

    [​IMG]
     
  9. strmrdr
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    by strmrdr » Jan 23, 2008
    Some people just like superior workmanship. :}
    Thats just as valid a reason as any other.
     
  10. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 24, 2008
    If these problems show up on the grading report and not in the stone (common) then Aldj, the wallet stays fatter with a good saving
     
  11. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 24, 2008
    Storm and John, I agree with the mind clean / workmanship issues.
    As long as our newbies know that is the issue - it is there choice.
    It is the religious conversion missonary [​IMG] factor that I disagree with. (Brian Gavin and I argue about it frequently over poor quality wine. But h tells me the quality of wine will imporve next time we meet [​IMG] )
     
  12. Paul-Antwerp
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    by Paul-Antwerp » Jan 24, 2008
    Hi Garry,

    First, I personally resent it when you are accusing Brian (and me for that matter) of religious conversion missionary talk. There is no ground for this.

    And with scintillation still being a scientific kind of no-man''s-land, there is indeed not a scientific confirmation of what many people prefer, both in rounds (H&A) as in some fancy shapes, like princess-cuts. In the same way, there is absolutely no scientific ground to dismiss it.

    So, as long as none of us has any scientific backing, I suggest that you stay away from the religious conversion missionary talk, just as we do.

    Live long,
     
  13. Regular Guy
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    by Regular Guy » Jan 24, 2008
    Paul,

    I am not Garry, and not only does he not need me to defend him...but I think I can speak for myself and cause my own hate mail in the process.

    Last night...I saw that there were in excess of 2500 people on this board. I''d never seen this many. Twice as many as right now. Surely that is a tribute to Leonid, Irina, and now Andrey, et al.

    How do they do it?

    Maybe it''s a lot of jazz.

    But...for my money...it''s the unhindered critical thinking available here. To what end? See below:


    What is the point where performance is effected? That IS the question readers ask here, and everyone wants to know.

    We DO freely, and with confidence, direct people away from the color D & E, frequently (not that there''s anything wrong with those), and likewise, readily tell most anyone VVS is a waste of money.

    Although the emphasis here is on cut...she we try to do no less for this C?

    Although I haven''t made my own significant studies of the impact of specific things like H&A...my investment in this site (well...no, not monetary) is with those who have done this study. For those considering spending THEIR money, and if I''m going to consider making a suggestion, I''d like it to be as informed as possible.

    Regards,
     
  14. strmrdr
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    by strmrdr » Jan 24, 2008
    RG..
    H&A fans will say that the well aligned facets return more light in difficult lighting conditions.
    Then the other side will say that hasn''t been proven! Then the fans say well it hasn''t been disproved either!
    Frankly I think there is truth too it that they do, but Garry will disagree or say not enough to matter.
    Who is right?
    No one can prove it either way.

    Remember that cut is only 6th on diamond performance list...
    Which is:
    1 lighting
    2 lighting
    3 lighting
    4 lighting
    5 lighting
    6 cut
     
  15. JohnQuixote
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    by JohnQuixote » Jan 24, 2008
    I'm with you here.


    'We' is somewhat broad Ira. I agree that the PS community as a whole tends to have a mitigating effect on highest color/clarity. That's coolish because - as a whole - people are getting their color/clarity impressions in commercial markets and that is not a realistic sampling of the kind of goods being offered by the top sellers here.

    To that end I think PS does a yeoman's job of making people 'critically consider' their color/clarity choices.

    BUT...

    Personally on Pricescope, and speaking for my company, we don't direct 'away' from any color or clarity. It's not our place to do so, as people have different values. One client may value high c/c as part of his/her cultural beliefs. Another may value the rarity. We don't presume to judge them as everyone is different.

    What we DO is to educate: If someone is not aware of how nicely a certain color/clarity will face-up when strictly graded and well-cut we do our best to teach them. To the delight of many this can be a money-saver for the client.

    What we DO NOT do is compromise on cut: First of all, the very 'face up' improvement in color/clarity described above is largely dependent on it. Secondly, it is the most important factor in diamond beauty. I've said many times I'll take a well-cut J/SI over a nailhead or fisheye D/VVS any day.

    With that said, I know you value cut Ira.

    I think what really gets debated here (in terms of rounds) is often the subdivision of precision within fine makes... It is (to use Garry's word) STOOPID that we don't yet have an additional finish grade called 'precision' which evaluates the patterning of the stone... It should be a craftsmanship grade. Just as with polish & symmetry the difference between EX and VG might not be a significant difference for some (or it may, depending on what we learn from AGS and Serg in the future) but at least it would further qualify the stone.

    You don't see this bickering about polish because we have grades for it. Those who want 'Ideal' can roll with the appropriate report. Again, it's silly that we don't yet have a category for the skill of the patterning/precision. It took GIA a long time to force a cut grade through and mass manufacturers resisted it tooth and nail. Good luck getting the constituency to buy into yet another criteria which will make top stones (not just 'H&A' but all nicely patterned stones) look good and average stones look...well...average.
     
  16. oldminer
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    by oldminer » Jan 24, 2008
    Strmrdr is right as he so often is.[​IMG]. In a dark room, a poorly cut diamond is just as good as a finely cut one. A high light return diamond is just as good as a miserable light return one.

    You have to have lots of light going into a diamond to get lots of light coming back out. The diamond acts like a tremendously complex lens in that it moves the light around and intensifies it in bright flashes while creating darker, contrasting zones of pattern which make the human eye say, "lookee there!!!" We have evolved a great distance from the lesser animals, but we still have very hard wired senses of pattern recognition and instinctual brain activity.

    Cut gives rise to interesting light behavior. Light gives rise to light return. You can have wonderful diamonds with super light return and relatively fair grades of cutting and you can also have diamonds cut with much concern for symmetry, and polish which still don't do great with appearance. Garry has a whole collection of relatively "fair" cut diamonds which have extraordinary beauty and high light return.

    This is not an either/or situation. It is just more complicated than what can be explained short of a book on the subject. Cutters have a trained method for handling this task, but most could not give you a detailed course on the science of it. They are hands on guys. To perfectionists, everything is of importance. To the mind clean types, nothing is ultimately important. To most of us, there are shades of gray which can be studied to have a working handle on how to find beautiful diamonds among the many offered. It is an art underpinned by a science, a complex affair. Off hand opinions of what matters most are not provable or likely to be more than somewhat on target.

    The end result must remain the test of trained eyes. Which do you prefer from those you looked at? If you looked at enough diamonds, then you can make an informed decision.
     
  17. gulliverseyes
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    by gulliverseyes » Jan 24, 2008
    Thanks for the responses. I like the concept that symmetry is not for everyone. I saw two diamonds recently, both were very nice, one had very symmetrical hearts and arrows and the other was quite uneven, like inside an ice chest. To be honest, as a newbie, the good H&A look was more of an interesting visual, seeing an even shape as if it''s an optical illusion. ...but the uneven diamond looked very nice as well, almost more natural. Personally, I think I could live with poor symmetry, but it would have to still look good to my eye. It seems like some diamonds with poor symmetry look like they have an uneven black box when you look down into them. I don''t like that at all.
     
  18. diagem
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    by diagem » Jan 24, 2008
     
  19. diagem
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    by diagem » Jan 24, 2008
    Dave..., I salute your writing and opinion here..., well said..., [​IMG][​IMG][​IMG][​IMG]
     
  20. JohnQuixote
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    by JohnQuixote » Jan 24, 2008
    DG, if you begin probing me in this area my replies are going to echo my personal tastes. I just want to be clear about that - I don't presume to speak for everyone.

    Increased brightness, dispersion and scintillation in a diamond can mask inclusions. Lighting must play it's part but that's a given in any scenario. Light getting in and out of a stone with more intensity can also result in less color face-up.


    Oui mon ami, but compare the G-VG-EX premium with SI-VS-VVS or J-G-D premiums, n'est-ce pas?


    Here we part ways, as I think the quality of a diamond's cut is what gives it life. I don't expect everyone to embrace that position, but on a consumer forum I champion the cause of cut quality because - in my experience - that 'life' is what makes the average consumer most delighted (I assume we're still talking about rounds and "ideal" cuts - as in the title of this thread).

    As for the 5 carater... Sure, I'll take the D/VVS if a recut is possible! [​IMG]
     
  21. diagem
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    by diagem » Jan 24, 2008
     
  22. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 24, 2008
    i am with John, there is a lovely 4ct D IF inside that 5ct D VVS.
    Give me an alive diamond over a dead one any day
     
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