GIA grading and med fluorescence - is an E really an E?

[Muppetina]

I''m hoping that some of the experts on the board can weigh in on this... I''m looking at a diamond with E color (I want a true colorless diamond, because I can see the color in a G) with medium blue fluorescence. My concern is that it has a very new (June) GIA certificate, and Marty Haske has stated that the new GIA color grading is done under fluorescent light and may bump the color grade us.

With that in mind, should I be concerned that the E is really an F or (gulp) even a G because of the blue fluorescence?

 

[valeria101]

Well... you do seem concerned. Does te diamond llok white to you? Until further notice, the GIA cert is what tells a diamond what color it is. Grading is not precise down to that level, so you bet ANY diamodn could return with one grade of color and/or clarity higher or lower upon regrading. Did you see the report on lab grading on the first page here? This is a senzitive tpic, so there is just one more such survey I know of...

So, really, these grades are not that precise, once and for all set, unfortunately.

The price will be set according to the grade on paper, and you will have to see the stone, of course.

On the other hand, given that different sellers have slightly different prices, you could likely find another stone, close in size and with a set of grades that make you absolutely confortable. This is harder with H&A or branded stones (since prices are more consistent)... but it shoud work.

And one more note: medium or stronger fluorescence gets D/F diamonds slightly discounted. If there is any reason for this (very debatable, btw.) than you just pointed it out

Hope this makes sense

From another perspective: a diamond's body color should be looked at with the stone placed face down on a piece of white paper folded at 90 degrees (L-shape). And for good reason - teh stone will reflect everything around anyway, so the faded white paint on the ceiling or the color of your skin or what not could make the diamodn look "tintend" when it is really not.

I fealt I should mention this, since "G" really does not show body color to me... I would think of "F" as a feel-good, no excuse white.

 

[quaeritur]

Hmmm... grading under fluorescent lighting should have no effect on a diamond with fluorescence, unless the lighting has a strong UV component. At least, that's my understanding. I have a D w/medium blue fluor graded by GIA and appraised independently w/the same result. I have no reason to doubt the color grade, at least not beyond the uncertainy Ana mentioned. I would not worry at all about an E color GIA graded stone, it should look colorless. And I say this from one color sensitive type to another -I generally see some body color in a G. Worst case, hopefully you're purchasing from a place with a full refund return period, so you can see how it looks to you.

 

[yowahking]

GIA has really slacked on their brownish tones K-P but the E should really be an E from them. I know some of the graders and they are pretty solid on top colors due to value.
Scott

 

[valeria101]

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On 8/19/2004 2:19:03 AM quaeritur wrote:

Hmmm... grading under fluorescent lighting should have no effect on a diamond with fluorescence, unless the lighting has a strong UV component. ----------------

Hm ... Right. This IS the question indeed. And THIS is the respective study by Martin Haske.


The Q seems legitimate and this would be a serious (=costly) problem if:

#1.grading would be perfectly precise in absence of fluorescence (which is not, at least within one grade, as far as I know)

OR

#2. the prices would be very, very strictly dictated by color alone (which they are not, as long as one can buy an E and an F of same weight and clarity, shape and cut from two sellers for the same or nearly).

Given that grading remains an art to some extent, how important this one grading factor is remains for each to think about.

Just my 0.2, of course.

Hopefully there will be some more informed interpretation on this thread.

 

[valeria101]

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On 8/19/2004 2:41:02 AM yowahking wrote:



GIA has really slacked on their brownish tones K-P but

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This sounds interesting! What is it all about?

One does not hear about these color grades too often on PS, but I am definitely interested... if you can spare 5min and a paragraph, of course.

 

[ChooChoo]

It would be great if some appraisers can weigh in with their experiences on this... have you seen DEF stones that look like they should be graded lower than they are by the GIA with medium fluorescence?

 

[oldminer]

We almost always agree with GIA color grading in the top levels, DEF. Yes, we see some that fluoresce, but I think it would be heretical to assert that the grades are false in some respect due to the UV color shift that "might" be happening. I can't recal one diamond where we felt the GIA grade was "false" because of UV fluorescence at this high color range. (D/F)




One can easily see color shift in some diamonds by masking their light source with a lexan shield and therefore eliminating the UV component. I think by the time one gets down to the H I J K L range some UV enhances an occasional diamond. Most of the time enough UV fluorescence makes the diamond a little cloudy, so the trade off for a grade better in color is diminished by a reduced beauty in appearance.




Stay away from strongly fluorescent diamonds. That's the smartest advice. You aren't going to buy diamonds by the hundreds. Make the ones you do purchase among the most desireable types. If you every need to sell a diamond, you'll be glad you bought ones that don't have "issues". Make it simple and let the market forces dictate value. You buy what's safest.




I personally wear a intensly fluorescent diamond every day. I enjoy seeing the nearly violet color appear in certain lighting and the regular body color appear when no UV is present. Now, why would I love such a diamond? It tells me the nature of the light in a room without giving anyone else a clue as to what is going on. Rubies look much redder in a UV rich light, darker diamonds that fluoresce can fool me with a false body color, and other things such as this. So, to me, this diamond is not only pretty, a little unique, but a valuable tool. Most folks would not like such a diamond as an engagement ring....That's what makes the diamond business special. Different opinions and different ideas of what makes something interesting or pretty.

 

[noobie]

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On 8/19/2004 10:05:47 AM oldminer wrote:







I personally wear a intensly fluorescent diamond every day. I enjoy seeing the nearly violet color appear in certain lighting and the regular body color appear when no UV is present. Now, why would I love such a diamond? ... So, to me, this diamond is not only pretty, a little unique, but a valuable tool. Most folks would not like such a diamond as an engagement ring....That's what makes the diamond business special. Different opinions and different ideas of what makes something interesting or pretty.

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No pics Dave? Are you holding out on us?

We want to see this pretty intense fluorescent diamond. OK, maybe it's only me, but others could be interested too.

 

[chrono]

Count me in as one of those who want to see your intensely fluorescent diamond. I've toyed with the idea of getting a diamond with strong fluor but have not been able to find one with all the specs I was looking for. Pictures please.

 

[Rowan]

I'd love to see it!!!

 

[Richard Sherwood]

Muppetina, if you want total peace of mind, you might consider sending it to Marty Haske for appraisal.

His SAS-2000 spetrophotometer takes fluorescence out of the equation when color grading. The graph report would be excellent additional documentation to have verifying (or not) the GIA grading.

This URL will show you a sample of the graphs:

http://www.gis.net/~adamas/sas2000.html

 

[yowahking]

Ana, in response to the lower color grades, I just don't get it but it has happened. For the last 6 months, GIA has changed it's grading of browninsh tone diamonds. A stone that sometimes gets sent to GIA hoping it stays at a J color with a tint of yellow will often ket a K. THey are hard on Yellow tint. But stones that people like David Atlas, or locally Bob Cloutier or Sindi Schloss, very respected appraisers, would bet a months pay that a stone will come back as a M - O - maybe P brownish color, now gets a K. I bought one after seeing many from dealers and laughing for months. I decided to keep on an maybe never sell it just to prove that paper does not mean everything no matter who does it.
I too like the Christmas light effect that some diamonds have. I often use them in my contest pieces with patterns, just to see if judges notice. They usually don't. Fun to do a pave design with a sprinke of colors hidden till you hit it with a black light at a dance club. Even a star of David, cross, smiley face, all fun little tricks of the trade. My appraiser has some photos of diamonds that he appraised with only the inclusion that flouresses, or only part of the diamond, or an unusual color like orange.

 

[oldminer]

Scott: Sure sounds like a large change in the works at GIA to have M-O brown tone stones coming back as K...All I can say is WOW, I'd lose a month's pay...Good thing I'm not much of a gambler.




The diamond game is continually evolving.

 

[quaeritur]

Yes Dave, do show us your ring!!! I would love nothing more than a strongly fluorescing e-ring, but I realize that's a very personal taste.