Sarin/ GIA and effect on cut class

[confusedbyhype]

Is the AGA cut class determined by the GIA cert or the Sarin report? What if the discrepancies significantly change the class?
Thanks!!

 

[dimonbob]

Hello Confusedbyhype;

In the first place you will never get a GIA or AGS cert to be exactly the same as a Sarin report. You will probably never get two Sarin reports from two differenct machines to be exactly the same and you are lucky to get two reports from the same machine to be the same. BUT...they are all close.

The problem is a .5% difference can change the AGA cut grade
either up or down which upsets engineering types. Boy & girls, diamond grading is not an exact science!!! Take your eyes off the numbers and LOOK AT YOUR DIAMOND! Just because a number is .05mm or .5% different is not going to change how it looks. The Sarin, Leveredge Guage or micrometer could be off by .05mm.

Oh, the AGA cut chart is not a GIA thing, but it will do until GIA gets off their dead thing and comes up with one of its own. Who knows, maybe GIA will take a short cut and buy the AGA cut chart from Mr. Atlas. NOT!

 

[confusedbyhype]

Thanks for the reply dimonbob. I'm not an engineer but perhaps I'm thinking like one. The ONLY objective criteria I have is that which is supplied by the vendor in the form of GIA/Sarin reports. I unfortunately do not have the benefit of seeing the stones prior to wiring my money. In fact the online vendor may not have even seen the stone. Such is the downside of purchasing over the internet.

Please let me know if there is another way or if I am missing something. Mr. Atlas' chart at least helps point me in the right direction and helps to separate great stones from fair ones. It's frustrating when a stone can go from a 1A to a 2A depending on which report you trust--GIA or Sarin.

Thanks,
Confused

 

[dimonbob]

Hello again Confused;

Why don't you post the certificate information and the Sarin information and let us all have a look at it.

I am sure you will get more then me posting answers.

 

[niceice]

Confusedbyhype, DiamondBob has been providing you with excellent advice. We wanted to comment regarding your comment pertaining to the diamond dealer who is offering you the stone may not have seen the stone. Unfortunately this is true of many of the diamond dealers on the internet, however there are many of us who won't sell a diamond without seeing it first, running our own proportions analysis, verifying the characteristics of the report, providing the consumer with clarity photographs, etc. and it is likely that one of these dealers would be willing to match the online price you've found for the diamond if they can source it. For instance, DiamondBob may very well be able to source it for you... Same with GoodOldGold.com; DBOF; ourselves and many others... There is no reason why you should have to purchase a diamond with limited details when so many of the online dealers are capable and willing to provide it for you. We would appreciate it if consumers like yourself would help us tighten up the ethics and business practices of the internet dealers by insisting on the information you are entitled to

 

[confusedbyhype]

The stone I'm referring to is a 3.3 ct Emerald cut diamond. The GIA cert notes that the depth is 65.2, while the table is 62 . However I see on the sarin report that the depth is listed as 66.4 and the depth at 61.5. The girdle is listed as STK -TK (4.5%) while the crown ht% is 13.2. So if I understand Mr. Atlas' AGA tables correctly, this stone goes from a 1B to a 2B (outside the 2%)(possibly from a 1A to a 2B) . I fully realize that the stone has not changed in beauty and that looking solely at the numbers is not the best way to judge a stone. I just wanted to know if when grading the stone would one tend to rely on the sarin report or the GIA cert. Is this much discrepancy common?


Thanks again to both of you as I've enjoyed your comments on this and other topics. Please realize that the consumer (who is very much a diamond novice) who is trying to make an educated decision must use all of the objective criteria available. Even if the seller had seen the stone previously I personally would put objective numbers ahead of subjective feelings as I would be suspicious of the motives of the seller. Please don't take that as an insult----this is the "buyer beware attitude" we take when using the internet to make diamond purchases.

Confused

 

[niceice]

CBH, while we've been quite successful in getting our OGI machine to measure round brilliant cut diamonds accurately in comparison to the information provided on the diamond grading reports issued by the GIA and AGS laboratories, we've yet to hit the nail on the head in terms of getting the same accuracy in measuring the fancy shapes... Thus we recommend using the information provided on the GIA lab report as the basis for your total depth and table measurements... Unfortunately the crown and pavilion measurements you are relying on will be slightly off because the other measurements provided by the Sarin are slightly off... Perhaps the seller can contact the cutter he/she sourced the diamond from and obtain the crown and pavilion measuements from the GIA for you (only the person / company that originally submitted the diamond to the GIA for grading can obtain this "proprietory" information)...

We would like to point out one thing... It seems to us that only David Atlas, the creator of the AGA cut scale can really make this determination for you because he is the only person that really understands the in's and out's of his scale... There really isn't an explanation on his site which provides a full understanding of the scale and thus you'll only be guessing at the results... Why not send the diamond to D. Atlas as a "condition of sale"?

 

[confusedbyhype]

Thanks for the great advice! Unfortunately, small discrepancies do apparently matter when grading the stone using the AGA scale.



Confused