GIA vs. AGS

[gemnewbie]

Do I need to be concerned buying an AGS certed diamond, as compared to GIA? Will the color and clarity grading match up for sure between the two? Would an identical stone be more expensive with one cert, compared to the other?

Many thanks.

 

[WinkHPD]

Date: 10/15/2009 6:12:38 PM
Author:gemnewbie
Do I need to be concerned buying an AGS certed diamond, as compared to GIA? Will the color and clarity grading match up for sure between the two? Would an identical stone be more expensive with one cert, compared to the other?

Many thanks.

There are about a thousand threads on this and perhaps even more opinions.

I think you might get many to agree that AGS is more restrictive on cut grading and that many in the trade prefer an AGS cut grade for truly top quality cutting and that both will usually be very close on color and clarity grading but no lab is in perfect sync with another, no matter how hard they try. Some border line grades will fall on different sides of the grading line if you send the stone to more than one lab.ut AGS and GIA are normally much closer to one another than not.

In the trade both are considered to be top tier labs.

There are many second, third and fourth tier labs that you will need to be much more concerned about as far as knowing what you really got.

Wink

 

[stone-cold11]

It is not a cert, it is just a report of the opinion of the color and clarity of the stone given by the labs. They did not and will not certify it.

 

[gemnewbie]

Thanks for the information and clarification from both of you. I used the word "cert" to mean certificate--I understand that labs do not guarantee the stones, but merely express opinions.

Do GIA graded diamonds generally sell at some premium compared to AGS? If so, how much?

 

[stone-cold11]

Ya, it is not a certificate. It is only a grading report. Certificate as a different meaning than a report.

AGS graded stones usually sells at a premium usually compared to similarly graded GIA stones.

 

[Rockdiamond]

Great point Stone-Cold. I have spoken to so many people that were mislead because they thought a stone was "certified"- when it ended up being "certified by Joe''s Gem Lab ( and hot dog stand)

gemnewbie I agree with Wink that the trade views both labs in the same high regard.
As Stone pointed out, AGS stones may trade at a premium - mainly due to the fact that there are a lot of folks that prefer the way AGS grades cut.

 

[Kelli]

I much prefer AGS, because I find their cut grading more reliable.

 

[diamondlove4]

If AGS is preferred, why to do high end jewelry stores (other than T&CO) use GIA?

 

[Lorelei]

Date: 10/16/2009 2:27:12 AM
Author: diamondlove4
If AGS is preferred, why to do high end jewelry stores (other than T&CO) use GIA?

GIA are still a highly respected lab and stores such as Tiffany will use them, basically both GIA and AGS are both very reliable for colour and clarity grading, AGS has an edge on cut it seems. Tiffany have their own set of standards for picking out their diamonds for cut also out of the GIA graded diamonds available.

 

[John P]

Date: 10/16/2009 2:27:12 AM
Author: diamondlove4
If AGS is preferred, why to do high end jewelry stores (other than T&CO) use GIA?

Addendum to Lorelei's comments:

I sometimes compare grading labs to universities. GIA is like an Ivy League school. So is T&CO. AGS is like the MIT advanced rocket-science program. A manufacturer will send each diamond (student) to the place he or she will have most success. The average to good ones (most) go off to universities with common standards (like EGL or IGI's finished-jewelry lab in the US). The fewer, more elite ones with the ability to score high or with a specialty are sent to the Ivy League (GIA). A few that will be worthy of passing the rigors of rocket-science (these will be sold to NASA) will go to MIT (AGS). And a few at the bottom of the pile will be sent to city college (Joe's Gem Lab and hot dog stand).

The above is meant as humor but there is a parallel logic. The path a diamond takes from cutter to lab to seller is chosen on-purpose, based on a number of factors which include the target market and knowing how well (or not) a diamond will score at one lab vs the next.

GIA has complete acceptance as the "foremost authority." This is reinforced by their reach, consistency and history. 10 out of 10 jewelers will agree because to dispute it would make them look silly. But be advised that the tales you hear about how other lab reports compare (oh...EGL is JUST as strict) or (T&CO overgrades for their store) or (AGS?...poppycock) or (My cousin's epic left eye graded this stone!...) will vary - and may or may not reflect reality/trade consensus.

 

[glitterata]

Hmm. I'm not so sure about that analogy, John. MIT is somewhat better than the Ivies in some areas (science, tech) and much worse in others (humanities).

I have a friend who graduated from an Ivy League school and went on to teach math at MIT. Same for physics. I don't know of anyone who graduated from MIT and now teaches a humanities subject at an Ivy. (Not to say there aren't any, but I bet there are a whole lot fewer, proportionally.)

 

[John P]

It's meant loosely, not literally dear.

I do feel it has merit as a broad comparison. Pricescope asked me if they could adopt it for their tutorial (right of page) and I've worked with a lot of consumers who found it helpful, but I have no doubt your specifics are correct.

And certainly (!) no offense intended to your friend, Marty H (w 2 degrees), my own cousin or anyone else with MIT paper... They are valuable ASSETs (get it?).

 

[Lynn B]

Date: 10/16/2009 1:44:31 PM
Author: John Pollard

Addendum to Lorelei's comments:

I sometimes compare grading labs to universities. GIA is like an Ivy League school. So is T&CO. AGS is like the MIT advanced rocket-science program. A manufacturer will send each diamond (student) to the place he or she will have most success. The average to good ones (most) go off to universities with common standards (like EGL or IGI's finished-jewelry lab in the US). The fewer, more elite ones with the ability to score high or with a specialty are sent to the Ivy League (GIA). A few that will be worthy of passing the rigors of rocket-science (these will be sold to NASA) will go to MIT (AGS). And a few at the bottom of the pile will be sent to city college (Joe's Gem Lab and hot dog stand).

John! I LOVED your analogy.
AND it made me chuckle!

My own li'l rocket-science major is currently in Richard Sherwood's hot little hands, and its preliminary grade for the semester is an "A"!

*happy sigh* Making Mama so proud!

 

[Texas Leaguer]

Prior posters have done a good job of describing the relevance and popularity of the major gemological labs(and the distinction between a report and a certificate).

It is pretty clear that knowlegeable consumers shopping for a top performing diamonds prefer the methodology and stringent standards of the AGSL. AGS established itself as the authority on diamond cut almost ten years before GIA began adding a cut grade to their reports on rounds. AGS remains on the cutting edge of performance analysis by offering cut grading on princess, oval, and emerald shapes as well as round.

What some folks might not know is that GIA and AGS have a common origin going back 75 years. The American Gem Society was established in 1934 by a group of independent jewelers and Robert M. Shipley, founder of the GIA.

While a GIA report is much more widely recognized in the broad market, which is an important consideration to many consumers, an AGS "triple 0" Ideal is a more coveted document to those interested in assurance of the best possible cutting.