What strength of fluorescence is this?

[Sparkle_seeker]

This diamond was graded medium blue fluorescence by GIA. It is a J vs1 ideal cut that faces up completely white. Recently it was worn to an event where there was blacklight, and it glowed a very bright, light blue. Does anyone think this might have been misgraded, and actually has strong blue fluorescence? I love the effect, and would be interested to know what strength of fluoro people here think it has.

 

[kenny]

Even if everyone who responds to this thread was trained to grade fluror (we're not) there are a zillion things affecting what each of us see when we look at your pic on our devices/monitors.
Fluor can only be accurately graded under controlled lighting conditions, and by trained pros, not by the general public and certainly not via a pic posted on the Internet.

GIA is, arguably, the most-trusted gem lab for very good reason.

Enjoy your beautiful diamond.

 

[EvaEvans]

It looks like Medium blue to me, not Strong blue.
GIA use fluorescent stones for comparison and you should trust their opinion.

 

[marcy]

It's hard to say for sure but IMO it looks like a medium to light blue florescent.

 

[whitewave]

This is my original engagement diamond. Yekutiel guessed this as very strong. Its uncertified and bought locally over 20 years ago, so we can only guess

 

[Rockdiamond]

It does seem to have quite a lot of fluorescence- but Kenny has a good point about monitors as well as so many other variables- so it's really hard to say by looking.
As a point of discussion:
GIA's FL grading only has four degrees of intensity. I believe that the reason is that it's harder to categorize degrees of fluorescence as compared to color or clarity.
Therefore GIA's fl grading is simply less consistent.
When we submit diamonds, I am more often surprised by a GIA fl grade than I am by color or clarity.

 

[Karl_K]

GIA grades FL at one wavelength range.
Science and my personal experience has shown there are many other wavelengths that diamonds respond to.
One I have seen was bright blue in sunlight, none on the report and in a GIA branded test box. Under a variety of different UV leak detectors with different wavelengths it varied from none to very bright appearing blue. There is a really long thread on this subject on PS.
So it is impossible to say what grade it is because it is not under grading conditions.

 

[Karl_K]

link to thread: https://www.pricescope.com/communit...f-blue-fluorescent-diamonds-revisited.219341/

 

[Texas Leaguer]

One of the most challenging aspects for consumers (and trade people alike) in understanding fluorescence is the confusion created by all the different devices available to stimulate the effect and the differential observations they give rise to. As Karl said, a given diamond may respond very differently to specific wavelengths. Even the same device may yield different results depending on the age of the tubes. GIA did an in-depth study on this topic a few years ago.
https://www.gia.edu/gems-gemology/summer-2013-luo-fluorescence-optical-defects
The bottom line quote from the article, and relevant to the question the OP askes in this thread, is "The variability in excitation wavelengths and bandwidths among commonly used lamps and LED UV sources demonstrates that the colors and intensities of observed fluorescence in a single sample can vary depending on the light source. "