Blue fluor - when does the whitening take effect

[GreenBling]

Hi

A jeweler commented today that my AGS I with medium blue could have graded incorrectly (too high) because of the fluor. I seriously doubt a reputable grading company like AGS or GIA would have misgraded a diamond because of the fluor (eyes rolling). But it does get me thinking about the "whitening" effect... I understand that the blue shows when exposed to UV light. My questions are: is the whitening a result of the UV + fluor? Or does the fluor simply cancel out the yellow without requiring presence of UV?

 

[sakari_8]

Fluor does help sometimes in color, it makes the color looks one grade up but I agree reputable
Company like AGS may not make mistake as such

 

[ecf8503]

Stones are not graded under UV light. They only turn on the UV light to assess the fluor. The electrons that cause fluor are only excited under UV light.

 

[yssie]

Hi

A jeweler commented today that my AGS I with medium blue could have graded incorrectly (too high) because of the fluor. I seriously doubt a reputable grading company like AGS or GIA would have misgraded a diamond because of the fluor (eyes rolling). But it does get me thinking about the "whitening" effect... I understand that the blue shows when exposed to UV light. My questions are: is the whitening a result of the UV + fluor? Or does the fluor simply cancel out the yellow without requiring presence of UV?

Short answer: fluor is an effect that can't occur without UV, yes.
Colour grading is affected by fluor, yes. (attached 2pg pdf exceprt)

Slightly longer answer re. "whitening": [URL='https://www.pricescope.com/community/threads/color-improvement-by-fluorescence.154811/']https://www.pricescope.com/community/threads/color-improvement-by-fluorescence.154811/[/URL]


Others worth reading:

Colour grading & fluor: http://www.whiteflash.com/about-diamonds/diamond-education/ags-laboratory-color-grading-of-diamonds-1249.htm
PS general article on fluor: https://www.pricescope.com/wiki/diamonds/diamond-flourescence
(Old but good b/c it's really easy to digest) article by Peter Yantzer on fluor grading. http://accreditedgemologists.org/lightingtaskforce/StudyonLongUVContent.pdf
Another (old) one you might find interesting re. potential effects of colour/clarity on light return: [URL='https://www.pricescope.com/community/threads/clarity-is-used-for-lower-light-performance-by-gia-and-ags.50121/']https://www.pricescope.com/community/threads/clarity-is-used-for-lower-light-performance-by-gia-and-ags.50121/[/URL]

 

[milton333]

Two things.

1. Your jeweler, like many/most, is expressing a bias against stones with flour. Possibly because he/she wants to sell you something "better." Historically, yes, some sellers would use UV light in store to make stones look whiter than their "real" color grade. It's an abuse that the Federal Trade Commission cracked down on, banning the use of the terminology "blue white" to sell diamonds. But lots of places, to show that they're "reputable," don't want to sell stones with flour, because of perceptions that it's a shady business practice. It sounds like your jeweler has either really internalized the idea that "flour is bad," or is trying to make you feel like there's something wrong with your stone, probably so he/she can sell you something.

2. Anecdotally, some folks believe that AGS grades color a bit more leniently than GIA. Maybe a color grade off. It is possible that your AGS I would be a GIA J. I don't necessarily believe it, but there have been several posters on here who claim to have seen this color grading disparity with AGS, so I'll put it out there as a possibility. Your AGS I might look to your jeweler like it's one grade off, not because AGS is mistakenly grading it with the UV light on, but because AGS may be a bit looser with color than GIA.

 

[GreenBling]

Thank you for responding to the post.

The jeweller is definitely bias against fluor. She said she prefers none. Also, she does not know AGS so she already assumed that the grading would be inaccurate (here in HK only GIA is recognized). She also got some of the facts wrong.

I think the problem with a lot of these local jewellers is that they have stopped learning years ago. Their minds are stuck in 'back then' so they are reluctant to embrace anything new whether it is the cut, technology, grading company etc...