shape
carat
color
clarity

Does this formula work?

Discussion in 'RockyTalky' started by FearlessSmile, Apr 7, 2019.

  1. FearlessSmile
    Rough_Rock

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  2. gm89uk
    Brilliant_Rock

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    by gm89uk » Apr 7, 2019
    What are you trying to determine?

    I made this excel sheet to help with calculating proportions:

    For GIA rounding things will not be exact because of rounding.

    www.gmsoft.somee.com/psdiamcalc.xlsx
     
    Last edited: Apr 7, 2019
  3. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 7, 2019
    2D942890-DE1F-4AAD-825B-D29CFD0C8610.png
    Thank you.

    I’m trying to work out the crown and pavilion angle. When I used the first method I got

    34.90249567 Crown angle
    40.69553104 Pavilion Angle.

    Does your spreadsheet show differently?

    Thanks
     
  4. gm89uk
    Brilliant_Rock

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    by gm89uk » Apr 7, 2019
    You can not calculate the accurate crown and pavilion angles as all those values are rounded.

    A good photo / ASET is worth much more
     
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  5. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 7, 2019
    F286CCDE-1987-4C30-BAE4-D1D84CA82777.jpeg
    This is the only photo I have, I’m only concerned with light leakage visible to the naked eye.

    My previous diamond was crown 34.5 and pavilion 41.4 (deep pavilion)

    I am led to believe the 35 crown and 40.8 pavilion works better and is unlikely to cause sufficient light leakage that would greatly impact the diamonds appearance to the naked eye?

    Thank you
     
  6. gm89uk
    Brilliant_Rock

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    by gm89uk » Apr 7, 2019
    35 and 40.8 are averages. Fluctuations may lead to leakage. Despite the tilted photo, there's an area with obstruction at 3'oclock from variation in the half pavilion mains which will most likely be associated with reduced light return/leakage.

    Are you open to other suggestions or are you working with a particular vendor?
     
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  7. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 7, 2019
    Thank you I’m based in the UK so have been looking at 77diamonds as they seem one of the most reputable here.

    Is this leakage likely to have a great visual impact from normal viewing distance and with it being GIA triple EX?

    Someone suggested it could be camera obstruction from above?

    Thanks
     
  8. FearlessSmile
    Rough_Rock

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  9. gm89uk
    Brilliant_Rock

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    by gm89uk » Apr 7, 2019
    It is obstruction, any black is obstruction. It's just obstruction from asymmetry from where there shouldn't be. I'm not referring to the clustering black ring between the arrow shafts, but the misalignment at at 3oclock under the table. You may be ok with it, I wouldn't buy a stone with it. If there was an aset or IS, those areas are often associated with leakage.

    I'm also from the UK and happily purchased from the US. Diamonds are an import business, so prices with VAT are all about the same.

    Are you buying the setting from 77diamonds or having it locally set? If you're buying a loose stone, it's much easier.

    Any reason you have a higher colour clarity combo? What is the cost of this stone inclusive of VAT?

    @sledge I believe already answered you about your calculation in another thread.

    You can not use a 57 table and 15% to calculate the crown angle.

    The table is anything between 56.5 to 57.49. the 15% CH is rounded from either 14.75% to 15.49% and is as such, more rounded than crown angles (which are to the nearest 0.5 degree)

    The pavilion height is rounded like the crown height. The pavilion angle of 40.8 is an average of 8 pavilion mains. The actual value can br from 40.7 to 40.89. odd numbers are rounded up to the nearest even decimal point.

    Ultimately if you calculated the perfect crown angle or pavilion angle average or acquired a sarin, it doesn't change the fact, there is some asymmetry in this stone, which is clear from the photo. It will probably be very pretty with localised leakage, that may be subtle, that you may never notice, or you may notice in a few weeks looking at it. As you seem very analytical, I would continue looking if it was me.
     
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  10. gm89uk
    Brilliant_Rock

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  11. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 7, 2019
    If you read the link above I’ve posted it’s saying from the camera lens and that people should not be put off by this? Thanks
     
  12. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 7, 2019
    The diamond is £2,843 and the ring setting is £577. Yes setting is at the same place too :)

    Is asymmetry more likely to be subtle if GIA has graded excellent? Thank you for your help so far I really appreciate it :)
     
  13. FearlessSmile
    Rough_Rock

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    by FearlessSmile » Apr 7, 2019
    I opted for colour F as wanted it to be colourless apparently no different between this and D-E. Opted for higher clarity as couldn’t find lower clarity that was eye clean with ideal proportions.

    Thanks
     
  14. gm89uk
    Brilliant_Rock

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    by gm89uk » Apr 7, 2019
    https://www.fourmine.com/shop/diamond/6322231780?utm_source=rarecarat&utm_medium=cpc
    (Although cautious about cloud as primary inclusion)

    https://www.fourmine.com/shop/diamond/1688018?utm_source=rarecarat&utm_medium=cpc

    https://www.adiamor.com/Diamonds/0....2.700&p=1&utm_source=rarecarat&utm_medium=cpc

    All work out cheaper including VAT and shipping.

    Please also re-read my posts and follow the link to the ASET. The area at 7oclock under the table is similar to the area at 3oclock in your selected diamonds. This is not the same as what Kenny was talking about in your linked post.

    Have you seen diamonds in person? Generally H coloured diamonds are plenty white for the vast majority and people are not able to see tint in it. I strongly advise you visit a B&M store and see GIA diamonds (AGS very rare in the UK) so you can calibrate your tolerance for colour.
     
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  15. Karl_K
    Ideal_Rock
    Trade

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    by Karl_K » Apr 8, 2019
    @gm89uk Good call it has wide ranging pavilion angles and twisted lowers.
    Based on the picture I would speculate they are all over the place.
    There are better diamonds out there without intentional issues.
     
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