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Fluorescence in D-E-F color Diamonds

Discussion in 'RockyTalky' started by Big Fat Facets, Jul 3, 2019.

  1. Demon
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    by Demon » Jul 8, 2019
    That doesn't hold up for chameleon diamonds though, does it? Because mine has a GIA report for natural color (and that it is a chameleon). I don't see phosphorescence with long wave, but I see it with short wave. (unless I'm totally confused by the chart, which could be the case lol)

    Or is this chart just for white diamonds?
     
    Last edited: Jul 8, 2019
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  2. Texas Leaguer
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    by Texas Leaguer » Jul 8, 2019
    I am not sure if GIA actually look for phosphorescence in the course of their fluorescence evaluation. I will see if I can find out. But I am sure they have done sample studies over the years to determine relative rarity of the trait.

    The property does not have much relevance to the consumer market, except perhaps among a very small number of collectors and diamond geeks, so I would not expect GIA to take extra time to check for phosphorescence on every diamond they grade.

    The majority of Whiteflash inspections are done to verify lab reports on the diamonds we sell. There has never been any particular reason for us to check for phosphorescence. But I think it would be interesting thing for us to sample for. Our production is geared toward negligible fluorescence so I suspect we will not find many phosphos!
     
  3. AV_
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    by AV_ » Jul 8, 2019
    Where do you heap the glowing rejects?
     
    Last edited: Jul 8, 2019
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  4. Texas Leaguer
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    by Texas Leaguer » Jul 8, 2019
    :) We don't reject them. Our Expert Selection category allows up to medium fluorescence.
     
    


    


  5. Texas Leaguer
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    by Texas Leaguer » Jul 8, 2019
    I heard back from a friend in the upper echelon of the lab world. It seems like phosphorescence would likely only be observed during advanced testing, especially in preparing certain fancy color diamond reports.
     
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  6. OoohShiny
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    by OoohShiny » Jul 8, 2019
    Would this sort of thing be related to the 'first water' diamonds that Yoram often mentions? :)
     
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  7. Texas Leaguer
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    by Texas Leaguer » Jul 8, 2019
    Yes, I believe so but I will let Yoram answer for himself. @diagem
     
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  8. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 8, 2019
    Yes, it is for colorless. Sorry - if I put the entire chart up it is headed that way.
     
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  9. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 8, 2019
    Melbourne. I think it is about the same as in USa except country towns can be tiny 1/4 to 1/2 ct etc.
     
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  10. Big Fat Facets
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    by Big Fat Facets » Jul 8, 2019
    Thank you so much for weighing in!!
    So amazing!! I have so much to learn!!

    Does a D-E-F diamond with fluorescence require microscopic examination by a trained individual to determine if the fluorescence has hindered that diamond's transparency??
     
    


    


  11. whitewave
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    by whitewave » Jul 8, 2019
    She lives in Melbourne and she is tiny! :sun::mrgreen:
     
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  12. Texas Leaguer
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    by Texas Leaguer » Jul 8, 2019
    Always a good idea to have a significant purchase evaluated by a qualified independent gemologist. Share with them whatever special concerns you have, such as the impact on transparency of fluorescence (or any other characteristic).

    It is also worth remembering that if transparency is affected by fluorescence, it will only be diminished in lighting environments dominated by intense UV radiation, such as outdoors in direct sunlight on a clear day.
     
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  13. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 9, 2019
    I use a fluorescent lamp tube that emits quite strong UV and hold the diamond very close to the lamp, slightly behind and slightly infront. I see the diamond only, not the bright lamp. If the stone goes blueish hazy petrol-ish (gasoline-ish) then I reject it.
    The stone on the left got sent back.
    No microscopes needed.
    Hazy Testing.JPG
     
  14. Big Fat Facets
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    by Big Fat Facets » Jul 9, 2019
    Garry,
    "fluorescent lamp tube that emits strong UV"
    is this a specialty fluorescent lamp tube or is it a common fluorescent lamp tube likely to be readily available...say... at a hardward store...???
     
  15. Big Fat Facets
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    by Big Fat Facets » Jul 9, 2019
    thanks Bryan!!
    you wouldn't happen to know of any qualified independent gemologist/appraiser in the los angeles area, would you??
     
    


    


  16. Garry H (Cut Nut)
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  17. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 9, 2019
    Yes, BFF, some tubes emit more short wave length and UV than others. It was what started the whole shootin match.
    GIA up till late 90's, or early noughties, were using lamps with heaps of UV and holding the diamonds being colour graded very close to the lamp - so diamonds with strong blue fluorescence appeared to be of a higher colour because blue masks the yellow (or brown) tints making the diamonds appear to have less tint.
    In maybe the mid 2000's they wrote an article 'admitting' the new color grading system (which was actually developed for their cut grading study). But to my knowledge there was never an announcement "This day we are changing our methods and you will get different results"
     
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  18. Demon
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    by Demon » Jul 9, 2019
    Thanks
     
  19. Texas Leaguer
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    by Texas Leaguer » Jul 9, 2019
    Excellent demo shot Garry. What are the stats on the two stones?
     
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  20. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 9, 2019
    Thx Bryan,
    No idea - I took the photo about 5 years ago. Returned the sleepy stone to the supplier. They have never sent me another dud since - I conduct this sort of training when I see them at trade shows. But that is getting harder because everyone is using LED lights now and there is hardly any shorter wave length light available at shows anymore!
     
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  21. AV_
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    by AV_ » Jul 10, 2019
    @Garry H (Cut Nut) I might ask if the left stone (or its type) is also less transparent with the UV emission strictly off...

    I find the subtle blue - intoxicating... Will certainly remember the use of 'salted' light.
     
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  22. AV_
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    by AV_ » Jul 10, 2019

    Now I am curious!

    I assume that the statement on rarity comes from a search through the archive of reports; the list of cases would be significant, because they'd be quite diverse as opposed to random, still statistics... If the argument is writtenn anywhere, I haven't seen it.

    One example of a colourless, phosphorescent diamond would demonstrate that it is worth looking for its kin among the more widespread types. The nature of the phenomenon might tell of how many might be expected (I haven't looked the matter up). One .01 would get the hunt going & it doesn't have to be cut.
     
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  23. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 10, 2019
    It would be, but the point I wish to make is there are many environments where there is abundant UV and near visible violet light that cause a lot more fluorescence and electron excitation. And the most powerful exiting frequencies pass through windows (contrary to some preachers views).
    So it is important that my clients diamonds do not go dull in many environments.
     
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  24. the_mother_thing
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    by the_mother_thing » Jul 10, 2019
    This needs to be a sticky, or perhaps quoted & posted in one of the “helpful links” threads. It seems to be a regular question that comes up, buyers inquiring about fluorescence and transparency concerns, and I think it’s hard to understand/visualize/articulate with words, but pictures ... super helpful! Thank you! :clap:
     
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  25. AV_
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    by AV_ » Jul 10, 2019
    I am making a note to self here that strong blue fluorescence may correspond to some prominent texture - substantial enough for the crystals to appear less transparent without the blue emission enacted; it does not seem obvious to me why these two go together & corresponding 'defects' are always intriguing.

    [Dam' beautiful blue! - that picture could 'launch a thousand ships'...]
     
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  26. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jul 10, 2019
    Sorry, I misread your question. With UV off I expect no fluoro haziness.
     
  27. Big Fat Facets
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    by Big Fat Facets » Jul 11, 2019
    Hi!
    Even though none of the diamonds below are colorless. I thought it would be interesting to show how they appear in sunlight...

    J color Medium Blue Fluorescence (almost 3 carats vs2)
    https://www.instagram.com/p/BpH3frUgw1S/

    M color Strong Blue Fluorescence (almost 6 carats si1)
    https://www.instagram.com/p/BopGgu8Ay9s/

    H color Very Strong Blue (almost 3 and a quarter carats vs2)
    https://www.instagram.com/p/BdyejwhgfjG/

    Please do share your observations...

    To me, only 1 diamond appears hazy.

    Thank you!=)2
     
    Last edited: Jul 11, 2019
  28. Wanaka
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    by Wanaka » Jul 11, 2019
    In order, my preference is the H/VSB, J/MB, and finally the M/SB. The M seemed very hazy and blue to me, however could that be an unfair observation as it is a lot heavier (presumably some spread too?) compared to the other 3-ish carat stones.

    I’d love to see a 3-carat plus, high-clarity D with VSB in real life! :bigsmile:
     
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  29. Texas Leaguer
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    by Texas Leaguer » Jul 11, 2019
    The M strong blue appears hazy. But it is also an si1, so the haziness may be a result of clarity features, or a combination of fluoro and clarity. Could also be that it needs to be cleaned. It would be good to see it in normal indoor lighting for comparison.
    The other two seem to have good transparency.
     
  30. Big Fat Facets
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    by Big Fat Facets » Jul 11, 2019
    Hi wanaka! im agreement with you. only the m strong blue appeared hazy to me, as well.
    the other 2 appear plenty transparent. I've seen and tried on all three of the rings. The m does not appear hazy milky blue like that out of the sun. In indirect sunlight ,from beside a south facing window, at around dusk, its a gray/brown tinged stone with visible inclusions, to my eyes.

    I might be able to share in a video clip of a 3 and a half carat D vvs for you some time next week...

    I love the green stone in your avatar!
    At some point, i'd love to find myself a beautiful sizable green columbian emerald
     
    Last edited: Jul 11, 2019
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