What is the real benefit of fluorescence, really??

[Jello88]

I have a friend who has an I color 3ct diamond with medium blue fluorescent. After she purchased it, she took it to a reputable third party gemologist/appraiser and asked him to tell her what he believed the specs to be without seeing the GIA report. He was so sure that it was either a F/G! I guess she got very lucky with her purchase I originally wanted a stone with fluorescence, but they seem to be a lot more rare to find? The more I learn about diamonds, the more I want to buy more haha. I’m also thinking about getting some round studs now too

 

[Rockdiamond]

That reminds me of a joke...
A Texan is talking to an Israeli.
"You should see my driveway in Texas- it takes 20 minutes to drive from the gate to the front door"
"Yes, I used to have a car like that" replied the Israeli

Point is....an appraiser who is incapable of color grading doesn't mean that we can draw a rule that an I with SB will look like an F-G

While I have seen stones who's face up color was improved by fluorescence, a trained color grader will recognize this and temper their judgment, and how they describe the color to the client.
Part of what the issue is in grading- some stones are just chameleons.
Not "real" Chameleon Diamonds ( that term refers to a specific type of stone) but more that some fluorescent stones undergo substantial face up changes based on lighting.
Others do not.

 

[Lorelei]

Hi Lorelei!!
Without a doubt such stones are pretty rare- maybe 20% of MB/SB...but that's a wild guess, I have not done a statistical study.
Back in my early days, at Harry Winston, this sort of stone in a higher color, ( D-E-F) was called a "premier". Such stones show an actual blue tint. They sold for a premium back then.
As Lorelei mentioned, fashion does change, and now such stones will be discounted as compared to inert stones.
I agree with Lorelei, there's no conflict between a "Super Ideal" cut and fluorescence. ( We've had super ideals with SB)

To be able to really see a consistent price difference, check on stones in high color clarity with no blue as compared to Medium and or Strong Blue. If you're looking at I-J colors, the general trend is far less discount for MB/SB as compared to colorless.


About the article Lorelei linked to- the conclusions are anything but agreed upon by experts. I find it to be misleading in a big way. Sorry

It's good to ' see' you David and thanks for the input!

The article was written by Michael and used in the tutorial section, do you think it would benefit from being edited in any way?

 

[Rockdiamond]

Lorelei,
Can I just say, you've been missed around here

Yes, there was a thread, probably 15pages long, that, unfortunately, got quite contentious, about the article.

The crux of the issue revolved around how much activation of fluorescence takes place, and where such activation occurs.
My experience is that in any lighting situation bright enough to distinguish the difference between a single color grade, many fluorescent stones get activated.
This includes daytime indoor situations with indirect sunlight.
Another point of contention regarding if GIA is or isn't screwing up color grading of fl stones due to the methodology they use, and how it relates to the first point raised.

 

[Lorelei]

You are very kind David and it's lovely to see you still posting, I've learned a lot from you over the years!

And you make good and valid points with this too.

 

[ChristineRose]

I think there was something said about fluorescence 'improving colour by a couple of grades' somewhere around, might not have been here but old stuff on the internet, but I don't think that's the case.

It adds interest to a diamond certainly and might have a slight effect on neutralising any warm tones a stone has in some lighting conditions, but that's all. Med to strong fluorescence isn't going to make an I colour look like a G or H.

You may be thinking of the controversy over the lights GIA uses to grade stones. They were supposed not to have enough UV to sway grades, but apparently they do.

In any case, you can't really define a grade without defining the lights under which it was graded, which means that the grade may already be including the subtle effects of the fluorescence.

 

[Alvain]

You may be thinking of the controversy over the lights GIA uses to grade stones. They were supposed not to have enough UV to sway grades, but apparently they do.

In any case, you can't really define a grade without defining the lights under which it was graded, which means that the grade may already be including the subtle effects of the fluorescence.

To further bring this issue into murky waters i think part of the controversy was GIA of yesteryears trained then gemologists to grade stones under lights that have negligible fluorescence as to represent the true color of the diamond rather than the fluorescent enhanced color.

Then GIA turned back on this philosophy and stated that the UV component in the lights used to grade the diamonds represents the typical lighting conditions when a diamond is viewed. However the distance for the sources of the lights are vastly different with grading lights being far closer to the diamond and hence higher UV component.

That's probably what caused the concerns of overgrading and the slight discount on fluorescent stones. If i am wrong someone please correct me.

 

[Lorelei]

You may be thinking of the controversy over the lights GIA uses to grade stones. They were supposed not to have enough UV to sway grades, but apparently they do.

In any case, you can't really define a grade without defining the lights under which it was graded, which means that the grade may already be including the subtle effects of the fluorescence.

Hi Christine,

It was from years before that but thanks for the suggestion, I should be able to find it and I won't rest till I do as it will be driving me mad! And absolutely, you can't properly assign a grade without efficient and controlled agreed conditions, things have changed a lot in recent years and not so much in others.