Article Over Grading of Blue Fluorescent Diamonds Revisited

[valeria101]

@drk14 It might make sense to account for the fact that diamonds are small objects

 

[Garry H (Cut Nut)]

http://www.idexonline.com/FullArticle?id=44211
HRD Antwerp says that a recent study it conducted on “The effect of fluorescence on the colour of a diamond", concludes that even strong fluorescence does not negatively impact a diamond’s appearance.


"In fact, the findings demonstrate the contrary: under normal conditions and even when outdoors, strong fluorescence has a positive influence on the color of diamonds. This finding directly contradicts the common perception that fluorescence is a negative property of diamonds, driving down their value. Given HRD Antwerp’s findings, they conclude there is no justification for the price penalties that currently apply to fluorescent diamonds."


Fluorescence, along with the 4Cs (carat weight, clarity, color and cut) is an important characteristic of a diamond and influences its value. Typically, in the diamond trade, it is perceived as a negative property, which drives the value of fluorescent diamonds down. HRD Antwerp undertook the study to assess whether this common perception is justified, and concluded that it is not.


To make this determination, the grading and certification lab wanted to identify how fluorescence influences the color grading results of diamond experts and gemologists in standardized laboratory environments, as well as to assess how fluorescence influences the visual appearance of a diamond for regular consumers. The latter was in fact the main purpose of the study: to determine the impact on the appearance of a mounted diamond as observed by an end consumer.


"The experiments HRD Antwerp conducted in its laboratory revealed several significant points, foremost of which is that diamond fluorescence has no influence on the color grading of a diamond in a laboratory environment, due to the insignificant UV content in conventional grading lamps. In short, fluorescence should not lower the official color grade. Furthermore, conventional grading through the pavilion (lower half) of a diamond in outdoor conditions actually improves the color grade for diamonds with a fluorescence grade above ‘medium’. As an example, a diamond graded in the HRD Antwerp laboratory as a J color with very strong fluorescence can appear as a D color when examined in outdoor conditions. When the diamond is examined through the table (face up), there is still an improvement in color, although this change is less significant.


"The results of HRD Antwerp’s study thus support findings from earlier studies conducted by other labs, adding additional objective assessments. It confirms that even very strong fluorescence has no detrimental effect on the appearance of diamonds in a laboratory setting, and when viewed through the pavilion in outdoor conditions, it results in a clear improvement in a diamond’s color. For the wearer or casual observer, fluorescence has a neutral or even positive impact on the appearance of a diamond, making it appear to be more colorless. Given these observations, HRD Antwerp concludes there are no grounds on which to justify the price penalties that currently apply to fluorescent diamonds."


Details of the study will be released during the HRD Antwerp lecture at the Hong Kong Jewellery & Gem Fair (AsiaWorld-Expo) on September 13 at 3pm in the AWDC lounge (Antwerp Diamond Pavilion Hall 5).

 

[Texas Leaguer]

It will be interesting to see the details of the study. As they say, the devil is in the details.

It is interesting that, at least in this summary, there seems to be the suggestion that there is nothing to the idea that strong fluoro can cause haziness, despite the fact that this effect is well established and well documented.
"...concludes that even strong fluorescence does not negatively impact a diamond’s appearance"

This makes me an immediate skeptic.

 

[Rockdiamond]

"...concludes that even strong fluorescence does not negatively impact a diamond’s appearance"

This makes me an immediate skeptic.

Finally we're in total agreement on this thread

 

[Texas Leaguer]

Finally we're in total agreement on this thread

Oh?

 

[Rockdiamond]

Oh?

Typed too fast...
Finally, we're in total agreement on at least one aspect of this thread

 

[Texas Leaguer]

Typed too fast...
Finally, we're in total agreement on at least one aspect of this thread

And which one is that?

 

[Rockdiamond]

Hi Bry
Can I call you Bry?

In any event- we both agree that HRD's statements are overly general- so much so that they strain credibility.

Have a great weekend Bry

 

[Texas Leaguer]

I'd rather you call me Boeing. It would make me feel rich and powerful

 

[Rockdiamond]

Ok Bo! ( I love nicknames

 

[Texas Leaguer]

Fair warning : Down here in Texas we call everybody Bubba.

I know how much you like nicknames, so if you call me Bo and I will be forced to call you Bubba.

 

[Rockdiamond]

Bubba....I love the sound of it. I’ll be the only one in 47th street for sure

 

[Garry H (Cut Nut)]

It will be interesting to see the details of the study. As they say, the devil is in the details.

It is interesting that, at least in this summary, there seems to be the suggestion that there is nothing to the idea that strong fluoro can cause haziness, despite the fact that this effect is well established and well documented.
"...concludes that even strong fluorescence does not negatively impact a diamond’s appearance"

This makes me an immediate skeptic.

I know one of the authors so asked him yesterday and he said transperancy is the next part of the study.
Michael. OH Miiicchaaaeel?

 

[Texas Leaguer]

I know one of the authors so asked him yesterday and he said transperancy is the next part of the study.

I will keep an open mind. I am sure there is something to learn.

But this explanation only adds to my skepticism. Is it intellectually honest to conclude " that even strong fluorescence does not negatively impact a diamond’s appearance", when the study has not looked at the primary concern regarding visual appearance?

Not only are transparency deficits known to occur in some fluorescent diamonds, logic dictates that the negative impact on appearance would be a matter of degree, not a simplistic yes/no proposition that many merchants cite rather dismissively.

 

[Garry H (Cut Nut)]

J appearing to be D is farcical though.
G to D maybe, or J to G.
I wonder if this stone was indeed an overblue milky stone. Or perhaps they searched and searched for an outlyer to make a point?

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Karl,

Thanks for this information. I had not heard of this problem with early white LED's:

"Some white LED (rarer now) use UV light + a phosphor to output white light thus, some UV will get out just like a florescent bulb.
If the phosphor is damaged or improperly applied the levels have been found to be very high.
Most newer white LEDs now use a royal blue LED combined with a phosphor so produce very little to no UV." Karl

Experience with LED illumination for the Over Grading of Blue Fluorescent Diamonds study showed a roll off in the visible violet (VV) with the result that grading of even strong and very strong blue diamonds yielded the "true body color" within the typical one grade margin of error.
This is documented on page 48 , Figure 12. in the pdf:
http://acagemlab.com/the-overgradin...-problem-the-proof-and-the-solution/#more-112

Michael

Dear Michael,
Are you prepared to walk away from your position on fluorescence yet?
Facts: in your research you used the wrong UV measuring instrument, ignored the fact that near visible and visible violet create the strongest N3 effect?
Ignorance to the fact fluorescent diamonds are brighter and whiter than the revised GIA grade in many lighting environments where there is actually enough illumination for consumers to observe color in near colorless diamonds?
Seems you ran away in all these debates as you seemed to be unable to answer these and other questions.
I put a lot of this material together for my book and posted a collection here:

Fluorescence

As blue is the complimentary colour to yellow, the most common colour in diamonds, blue fluorescence can make yellow diamonds look white or colourless.

www.hollowaydiamonds.com.au

 

[Karl_K]

This thread was a lot of fun back in the day.
Call me jaded but you can find an odd stone to prove about anything because there is a huge variety of material out there.
But the one you found may be the only one out there.