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Appraisal discrepancy: Some Questions for the experts.

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DKinLA

Rough_Rock
Joined
Mar 4, 2009
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75

When I had my recent purchase appraised yesterday there were a few discrepancies with the GIA cert. I used Patrick Davis in LA who was an excellent educator and spent almost two hours with me examining the diamond. He did not look at the GIA cert before the appraisal.


The discrepancies were
1. Clarity: GIA cert was VS-1, Patrick says it’s VVS1 (only one inclusion found under a bezel facet. This matches the plot on the cert. We looked and looked and couldn’t find anything else.
2. Fluorescence: GIA cert was Strong and Patrick thought it was more Medium blue. This is an E colored diamond. Patrick did say that he noticed a slight change in the light refraction under certain light conditions due to the fluorescence. He said it was like Los Angles on a hazy day. He however only said this after putting it up against a black light and determining it had fluorescence. Beforehand he never mentioned it. He said that all fluorescent diamonds have this and this is why they are discounted. I couldn’t see the change in refraction he was referring to and I have a keen eye. Is this something to be concerned about – EXPERTS PLEASE WEIGH IN HERE

Unfortunately his Sarin machine is out for repair so I couldn’t get the actual, non rounded numbers of the stone. He manually checked the crown angle and it fell in line with the cert which was 33.5 degree CA with a PA of 41.0. He verified the cut and said it had perfect H&A and was extremely well cut. He noted “slight” table leakage under the ideal scope, not the ASET, and didn’t think this was anything to worry about or anything eye visible.



Questions:
1. Can GIA really be off two clarity grades?
2. Does fluorescence affect the light refraction in a diamond even if it doesn’t look milky?
3. What do you think about the comment regarding light leakage under the table? Can anyone model a 33.5 CA, 41.0 PA, T=57%, Depth 61.2%

Sorry for the long message and TIA.
DK
 

denverappraiser

Ideal_Rock
Trade
Joined
Jul 21, 2004
Messages
8,810
1. Can GIA really be off two clarity grades?
Sure. It’s also Possible that Patrick is off or a combination of the two. Talk with Patrick about this. Ask specifically if he's confident that it's the correct stone for the report.

2. Does fluorescence affect the light refraction in a diamond even if it doesn’t look milky?
No. Not under normal lighting conditions, which contain no UV component to speak of. Even under high UV conditions like the discotheque or the tanning salon it's not the refraction that's being affected but it does substantially change the 'look' in those environments.

3. What do you think about the comment regarding light leakage under the table? Can anyone model a 33.5 CA, 41.0 PA, T=57%, Depth 61.2%
Ask Patrick to explain the details of his report and his methodology.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 

DKinLA

Rough_Rock
Joined
Mar 4, 2009
Messages
75
Thanks for the quick response Neil.

Patrick is confident that the stone and cert match. His appraisal will officially say VVS2 (in between) since he doesn''t believe it is a VS-1.

I have another diamond with medium blue fluoresence and I would say this one looks very similar. I like fluoresence in diamonds - the blue flashes and slight purple/blue tint the body color takes on when in direct sunlight really make is sparkle. I''m also a science geek and appreciate the concept of UV light excitation of boron electrons. I don''t have a diamond of similar size without fluoresence to be able to compare other factors- like fire, contrast etc. in different lighting conditions. My question is, aside from the purple/blue body color hue change, are fire and scintillation affected? Assuming this is not an overblue that is oily/milky/hazy etc. In the past, going back about 5 yrs, when I compared fluorescent vs. non-fluorescent stones I didn''t see any impact. Now I''m second guessing myself.
 

denverappraiser

Ideal_Rock
Trade
Joined
Jul 21, 2004
Messages
8,810
Fire and scintillation are both a function of cutting. Clarity can affect it to the extent that it affects transparency (an ideal cut sugar cube would still not show much life) but UV fluorescence is not a variable that affects either one.

You got a VVS2 for a VS1 price. To paraphrase Martha Stewart, that's a good thing. Stop worrying and be happy.


Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 

DKinLA

Rough_Rock
Joined
Mar 4, 2009
Messages
75
LOL


Neil I am happy. I''m simply on a quest to learn as much about my diamond as possible.

Any other thoughts on the CA & PA combo?
 
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