New fluorescence conclusion???

[IrishEyes]

Hey everyone! Got a question for some of you "in the know"! Today my boss told me that it was recently published in some gemological journal (can''t remember where or who did it) that fluorescence has NO effect on color in lower-colored diamonds, say K and below. While I was always told (even in a GIA diamond grading class) that fluorescence was an acceptable attribute in lower-colored diamonds, apparently he says that is not true and that recent studies have determined otherwise. Is this true??? Does anyone know, cause it sounds fishy to me. Like I said, as of this past August when I did my GIA grading class, fluorescence in high-colored diamonds was generally not too good, while fluro in lower-colored diamonds was acceptable. It''s just sounds weird that suddenly that has changed. Thanks for your answers in advance!

 

[belle]

irisheyes,
gia did a study on fluorescence, but it was limited to stones of k color and higher. i think you will find the relative answers to your questions here. you will want to download the pdf. version at the bottom of the page.

 

[perry]

I find the concept that flouresence not affecting grading in the "fancy" colors (K, L, M...) to be belivable. How do you affect color much in something that is "srongly" colored already?

Of course, how many K or lower diamonds are you selling?

Perry

 

[valeria101]

I would surely like to see this new survey!


I am writing this more to clarify things for myself, I am not an expert. You can at most count one account of personal impression of fluorescence and color grades.

Once upon a time there was some GIA survey on the visual imact of fluorescence on grade D to K. Not below. The conclusion was ambiguous - allot more ado than anyone could see unaided, either experts or casual observers. I have to agree because it takes off he chart fluorescence in a white diamond for me to see anything. Garry posted those results on this forum somewhere - the copy he sent me has fallen victim to former laptop meltdown

The new result you mention for K-Z sounds reasonable - you've got that faint and temporary effect of fluorescence dependng on invisible properties of the light environment... that some already visible color tint would be changed but not covered up by it. So those diamonds would always look 'tinted' only a bit more or less so depending on whether the fluorescence is taking effect. If the stones are never 'white' that can't make a huge difference in their price / value, I guess. Perhaps this is what the article you mention is trying to say? In contrast, GIA's studies did not go down to those grades and did not explicitly evaluate the impact on price because they concluded there was no significant visual effect to talk about in the first place.

Down to light yellow it shows more (still the strong one), IMO, but the statement that this effect has little impact on cost makes perfect sense because even the color grades in that range do not clumped together as they are.

Am I wrong to believe that there is way more talk about fluorescence than any visual impact it may have?

 

[WinkHPD]

Here is an excerpt from the report. As you will read, not only does fluorescence favorably affect the appearance of deeply colored stones, but many found it to also pleasantly affect the appearance of colorless stones.

I can say that when I came into the trade well over thirty years ago we charged a premium for medium to strong fluorescence, provided that the stone was not "overblue". This changed during the investment craze, when fluorescence came to be a negative according to the paper sellers. This study only reinforces my own perceptions and I am glad to see that these old eyes have not deceived me all of these years...

Quote:

This study challenges the perception held by many in the trade that UV fluorescence generally has a negative effect on the overall appearance of a diamond. In fact, the results support the age-old belief that strong or even very strong blue fluorescence can improve appearance rather than detract from it, especially in diamonds with faint yellow body color. This result is consistent with the slightly higher 'asking' prices reported for these stones. While the apparent benefits of blue fluorescence are less obvious in colorless to very near-colorless diamonds, they still were evident in the study. This should bring into question the trade's lower 'bid' prices for moderate to highly fluorescent diamonds in the better colors. It also makes us question the source of the present controversy surrounding fluorescent diamonds. It may be the result of trademembers' misunderstanding of the complexity of the issue, or the extreme price sensitivity in the highest color grades (where there are fewer stones and distinctions are more subtle). Or it may be the fact that it is simply easier to move goods without the encumbrance of a reported fluorescence.

End quote:

Wink

 

[valeria101]

Date: 10/11/2005 6:24:30 AM
Author: Wink

Here is an excerpt from the report...

Quote:

... the results support the age-old belief that strong or even very strong blue fluorescence can improve appearance rather than detract from it, especially in diamonds with faint yellow body color.

End quote.

Wink

Does ''faint yellow body color'' mean I-K or N-U/V in this context?

It sounds a bit counterintuitive for the strongly tinted ones that are sold as near-yellow rather than ''almost white''.