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question regarding GIA-princess cut grading and performance

samnhean

Rough_Rock
Joined
May 18, 2012
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Hey guys, looking to buy my first diamond, ended up of course having to sign up for a PS account :) So far, I've done tons of research. I hate to beat a dead horse regarding GIA certification for princess cuts, and I know that getting an AGS0 graded princess will give me ideal fire and brilliance. However, I refuse to believe that a majority of the nicely specced GIA-certified diamonds out there may lack the performance only because they weren't visually inspected for fire and brilliance. Almost all of them lack an ASET certificate, which is why I am geared towards Whiteflash's AGS0 princesses. I keep reverting back to youtube videos from Good Old Gold, like this one. http://www.youtube.com/watch?v=b14VjeAgfyk..... It states no matter how good the cert is, you still need to do a visual check for optic performance.

Is this to mean that if I go out and find GIA-certified diamond with these example specs:

1ct princess
E color
VVS2 clarity
ideal cut, something like 68% depth 68% table, ex polish ex symmetry
1.0 ratio
thin to medium girdle
no fluorescence

there is still a chance it won’t perform nicely?? The guy is really adamant that you have to visually inspect every diamond and that no matter how good the GIA specs are, they just aren't enough. I find it hard to believe that I can see a poor performing diamond with such good specs. A comparable AGS0 would go for a few hundred dollars more just for the cert. Thanks for your responses!!

lastly, an 05 article regarding AGS certification for princess cuts seemed to lean more towards smaller tables in the 50-60% range for performance. Is this still relevant?
 
Re: question regarding GIA-princess cut grading and performa

samnhean|1337389850|3198835 said:
...there is still a chance it won’t perform nicely??

Yes. GIA does not provide any cut grade for the princess shape. A GIA graded princess can be a firecracker or a lifeless dud, and there is no way to tell from the grading report.

You can see if the basic indicators are promising (a simple reference is provided here: https://www.pricescope.com/wiki/diamonds/diamond-grading-chart-princess ) but there are variables involved in fancy shapes that are unaccounted-for by limited and averaged numbers. As an example; do you know how many pavilion facets the princess you're considering has? Depending on whether it's a 2,3,4 or 5-chevron configuration it could have between 24 and 48 facets...and there will be no notation about it on the grading report (other than the clarity plot, if present).

Cut assessment for fancy shapes is about 100 years behind cut assessment for rounds - which is still in its infancy. So it's important to understand that while color and clarity are held to established standards there is no standard whatsoever enforced for (arguably) the most important appearance component.

The guy is really adamant that you have to visually inspect every diamond and that no matter how good the GIA specs are, they just aren't enough.

Bottom line: The guy is correct.
 
Re: question regarding GIA-princess cut grading and performa

He's right! You absolutely CAN NOT buy a fancy cut diamond based on the numbers alone. :wink2: That's why buying an AGS0 makes it much more simple, because it's already been evaluated for you. And your right, that doesn't mean that the GIA graded stones lack wonderful light performance, it just means that you need more information before you can make that determination. If you find a GIA stone that you like, your next step would be to request ASET images to evaluate the performance. =)

EDIT: oops John and I posted at the same time, sorry I didn't mean to repeat it.
 
Re: question regarding GIA-princess cut grading and performa

hhmm, I"m getting a server error when I try to pull up the stones. Can you double check the links for us?

John, as a trades person won't be able to give you an opinion on the stones you posted, they are limited as to what they can say. But anyone else can and we'll be happy to help. =)
 
Re: question regarding GIA-princess cut grading and performa

looks like WF site is down for maintenance. even whiteflash.com doesn't work.
 
Re: question regarding GIA-princess cut grading and performa

samnhean|1337392542|3198877 said:
looks like WF site is down for maintenance. even whiteflash.com doesn't work.

sorry! :(sad I was just coming back to post that. I went searching for some options for you, but as you know, they are down. Have you taken a look at Brian Gavin Diamonds? He actually worked for WF before starting his own company. He's wonderful and there are many many happy PSer here that have used him. =)
 
Re: question regarding GIA-princess cut grading and performa

WF is back up if you don't mind taking a look at those 2 ASET's and tell me what appeals more to you :)
 
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