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what is this shadow in my diamond?

Discussion in 'RockyTalky' started by genie, Feb 10, 2001.

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  1. genie
    Rough_Rock

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    by genie » Feb 10, 2001
    Hi, I just got engaged in Oct and FH bought me a wonerful E-ring, but something is bothering me. I have a round brilliant. It shines and sparkles great most of the time, but in certain lights, if I tilt my hand toward my body, I start to see this shadow in the center of the stone. Since there is no shadow when i look at it head on, is this normal or "ok?" Or does this mean, that it's cut is not good? Thanks for your help!
     
    


    


  2. genie
    Rough_Rock

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    by genie » Feb 10, 2001
    Gary or Leonid,could you please check on these numbers. 62% depth
    56% table
    crown angle 34.8
    pavil angle 41.2
    culet is 0.9%Thanks,Genie
     
  3. genie
    Rough_Rock

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    by genie » Feb 10, 2001
    HI Gary,
    I read about fish eye and it says that it usually is for a shallow depth or thick girdle. My diamond is GIA certified so the only thing I know about its proprotions are:
    Round brilliant: 5.66-5.71x 3.63 mm
    Depth: 63.9%
    Table: 55%
    GIrdle: thin to medium, faceted
    Cutlet:none
    Finish:
    Polish - Very good
    Symmetry - GoodCan this shadow I see sometimes, be instead "nailhead" as a result of the too deep total depth? I have read that it is ideal to go no deeper than 63% and on some sites it says no deeper than 62.5%
    As I mentioned before, I don't see it when looking at it dead-on (it's absolutely maginifecnt). When I tilt it down, that's when I see it the most. Sometimes, I can see darkish areas when looking at it from the side too. What do you think? Mediocre cut?
     
  4. pricescope
    Ideal_Rock

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    by pricescope » Feb 10, 2001
    Genie,These numbers looks better than for previous one. I guess it is AGS0 graded stone, right? If so you would be asked to pay premium for it. Please be aware that AGS0 range is too broad and not all AGS0 are equal.41.2 is the most deep pavilion allowed for AGS0, 0.5 degree deeper than Tolkowsky. In combination with 34.8 it causes a partial light leakage under the table. See www.pricescope.com/tutor_agsideal.asp .Have a look at the light return plot from MSU cut study research, www.cutstudy.com/cut/english/document4_1.htm . You can see how light return drops below 1 (Tolkowsky) at this combination of crown and pavilion angles. [​IMG] Another example of the deep pavilion effect on the diamond performance you can find at www.goodoldgold.com. This AGS0, www.goodoldgold.com/148.htm,
    has 56% table, 34.7° crown and 40.5° pavilion angles. It has very high readings on Brilliancescope and rated Excellent on HCA.Another one (almost like your stone above), www.goodoldgold.com/newpage35.htm , 55% table, 34.8° crown and 41.1° pavilion angles, has much lower Brilliancescope reading and HCA score only Very Good.
     
    


    


  5. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

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    by Garry H (Cut Nut) » Feb 11, 2001
    The problem is likely to be a bad combination of drown and pavilion angles. If you can return the stone, then do so. This stone can not possibly have good proportions from the limited data. I ran the most likely proportions through the cut adviser and these are the results.
    Selected: 63.9% depth, 55% table, 35° crown angle, 42° pavilion angle
    Brilliance Good
    Fire Poor
    Scintillation Good
    Spread or diameter for weight Good
    Total Visual Performance 6 - Fair
    Sorry, Garry
     
  6. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

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    by Garry H (Cut Nut) » Feb 11, 2001
    Sounds like you are seeing the girdle. This is called a fisheye effect when it is obvious with little or no tilting.
    In the Tutorial on this site go to the fisheye section.
    Garry H
    PS do you know the stones proportions?
     
  7. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

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    by Garry H (Cut Nut) » Feb 11, 2001
    Just had my new computer loaded - so i missed all this.
    I dream of customers like you genie. But you have all your wishes now! You will never regret any of these stones - they are all within the top 2-3% of diamonds based on cut, so dont split hairs - make a decision now on price, service and the other C's.
    Garry
     
  8. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    Leonid,you were right. Could you check on one more please? here are the specsdepth 61.5%
    crown angle 34.0
    pavil angle 40.9
    table 56%
    culet 0.9%thanks,Genie
     
  9. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    Genie, much better now: HCA Excelent total score with Excellent Brilliance and Fire!In this case a bit deeper than Tolkowsky pavilion angle is compensated by a shallower crown.Did you find it in the Internet or in the local store?
     
  10. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    Garry,
    Thanks. HOw accurate is that cut adviser since you didn't know the exact crown and pavillion angles? I am still in a bind about what to do. My fiance wants to get me another diamond, but I don't want him to unless this "shadow" is real or if it's just because in certain lights diamonds cannot reflect back the light well. Thanks for your help! I appreciate it.
     
    


    


  11. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    THanks to everyone who helped me and my fiance! We are most likely going with this one I found later. It's a 0.6 on visual performance!(on the cut adviser came out on top over the two I was previously considering)Table 55%
    Depth 61.6%
    Crown angle: 34.4
    Pav angle: 40.7
    Pav % 42.6
    E
    VS2
    A Cut Above heart and arrowThis one was a little better in price, maybe because it is a smidge lighter (.72)? What do you all think of this one?Oh, lawmax, my fiance also didn't like the 53% table on that other one!
     
  12. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    looks like a winner to me [​IMG]
     
  13. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    o-oh... there is no limit for that, you know [​IMG]
    The last diamond should be very nice. Although if you want more perfection you can look at "super ideal" branded Hearts and Arrows diamonds like A Cut Above ( www.whiteflash.com ), Aglaia, Hearts on Fire ( www.heartsonfire.com ).
    Next level would be EightStar diamonds, www.eightstar.com .
    It is always a good idea to see many different diamonds. You can try to find knowledgeable dealer who carries different brands and decide yourself what make you want.
    Lawmax followed the same way, I think, and ended up with EightStar [​IMG]
    However, even if you'll decide to go with any brand name diamond, don't forget to check them by the Cut Adviser as well.
     
  14. lawmax
    Brilliant_Rock

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    by lawmax » Feb 11, 2001
    Hi Genie,It's tough when you can't compare the two diamonds. You could have them both sent to an independent appraiser (many dealers will send stones to Dave Atlas www.gemappraisers.com or Bill Lieberum www.consumersgemlab.com (he's out of the country right now) before the consumer actually pays for the diamond. Then you pay the appraiser's fee for examining both diamonds.Personally, I would not pay for the "c grade" hearts and arrows pattern. I would go for the best possible symmetry.Also, I think the magic of extremely well-cut diamonds is the fire they produce, especially in dim lighting. It is easier to produce diamonds that are brilliant than it is to produce highly dispersive diamonds. The rainbow flashes can be awesome. I realize the difference here may be minimal, none, or something else.It is hard to tell you which diamond you would like better-I'm sure they are both very beautiful. I think a 53% table is quite small. I would doubt that you would see the difference betweeen the D and E colors, especially after they are mounted.Hope this helps,lawmax [​IMG]
     
  15. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    THanks again Leonid!
    This story just gets more and more confusing to us. I called whiteflash (Cut Above) and they said its very important to have a perfect heart and arrow pattern. He says theirs are near perfect/perfect. The other diamond, is what they call "heart and arrow:C" because the hearts are not exactly all the same size and that one of the arrows was shadowy.
    Despite this, you say the first one will be more brilliant? Which one will be the better (visually more beautiful)? The Cut Above sounds good to me - the only thing about the other one that is better is that it's D in color. There's not much difference between D and E to a layman right?
    I know you are probably skeptical to tell me what to do, but you are the expert. I want the stone that is more well cut and thus more brilliant and sparkly (color between D and E is not as important). THe price diff is not that significant. Thanks Leonid!
     
    


    


  16. lawmax
    Brilliant_Rock

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    by lawmax » Feb 11, 2001
    Looks like an excellent choice-enjoy it! [​IMG]lawmax
     
  17. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    Thanks Leonid!
    Is this about the best you can get, or is there something higher than Excellent brilliance and fire? My FH figures if he is going to get me another one, that it be the best we can afford.
     
  18. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    Genie, based on the proportions above both stones should be great and scoring below 2. Less than 1% culet shouldn't bother you.

    A few tenths difference in the HCA score should not be a decisive factor. There are others. Since both stones are H&A you have to make sure whether H&A pattern is prefect. A Cut Above diamonds are known for its consistency. You have to use H&A viewer to see whether H&A images are perfect (see Hearts and Arrows Diamonds and The Basics of Diamond Cutting ).

    The first one has D color while the second one E. You have to weight all these factors plus price.

    One more small note. Because of proportions the first diamond can be a bit more brilliant but less fiery than the second one.
     
  19. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    Genie,63.9 total depth is too deep. It drags the cut into 3A AGA grade. Although we don't know exact crown and pavilion angles for your diamond we can try different combinations that together with girdle thickness will give you total depth.Garry and I have Diamond Calculator that makes it very easy. If you’re using Internet Explorer you also can play with numbers using this tool: http://www.cutstudy.com/cut/Brill/e_ray_thin.htm. Having fixed total depth 63.9%, 55% table and 3% girdle you can have certain combinations of crown and pavilion angles. E.g.:Crown angle – Pavilion angle
    32.6 - 44.0
    33.0 – 43.0
    35.5 – 42.0
    37.9 - 41.0None of these combinations as well as anything in between will give you the best result.leonid
     
  20. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    THanks for all your help Leonid,
    You know, I tried to use the cut adviser myself, but it would say that I have to register. After I put in my info, it says that I am already registered and to check my info. Huh? Can't seem to access it. That's why I have been pestering you with the numbers! What is the problem?
     
  21. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    Genie, first of all I'm not an expert in a literal sense - just have learned something myself and with the help of the real experts. [​IMG]When I said the first one is a bit more brilliant while second one has a bit more dispersion (fire) it is only in theory and the difference can be very slight. One has to eyeball both them to tell.I agree with Whiteflash - if you are going to pay premium for H&A, you might what to make sure that the diamond is a true H&A.On the other hand, although you won't see the difference between D and E, there is a difference in the market price.Darn! Tough situation! [​IMG] Could you get H&A images for both diamonds? What is more important for you: superior cut or the color difference?
     
  22. pricescope
    Ideal_Rock

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    by pricescope » Feb 11, 2001
    That is known problem [​IMG]If one tries to use the aviser without registering first, it behaves this way. If you'd send me your email address, I'll register you and email you your username and password back.
     
  23. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    Leonid,
    Thanks for the password! When I tried it though, my second stone had excellent brillince and very good fire. Maybe I did it wrong? I need some expert advice. Which one would you buy?The stone above:
    Heart and arrow
    crown angle: 34.2
    pavillion angle:40.9
    table: 55%
    total depth: 61.5%
    D color
    VS2Or this one:
    A CUt above heart and arrow
    crown an:34.7
    pavil an: 40.8
    table:53%
    total depth: 61.9
    E color
    VS2The Cut above is about $160 less and 0.14 carats lighter. When I ran this in the cut adviser it gave excellent brilliance and fire, I think 1.8 score. THe other one gave a 1.7 score. Please check me on this?
     
  24. genie
    Rough_Rock

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    by genie » Feb 11, 2001
    Leonid,
    I just noticed! My fiance gave you the previous specs that you said were excellent. He had some type-o! Mine are correct. Cutlet is 0.9% for the first and none for the CUT Above one. Thanks!
     
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