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Results of AGS Graded Lab Diamonds vs. IGI & GCAL

Ada Diamonds CEO

Rough_Rock
Trade
Joined
Jan 8, 2020
Messages
69
We were invited to participate in the pilot phase of AGS's return to grading lab diamonds, and we have the results back from our first few batches graded by AGS. Most of the stones we sent were previously graded by IGI or GCAL so I am sharing the results with the community to address the 'conventional wisdom' about IGI grading.

The vast majority of diamonds we submitted to AGS for secondary grading received the same color and clarity grades as their first grading. When AGS differed from IGI or GCAL, the results were only off by one (E vs F color, VS1 vs VS2). More often than not, AGS was looser/easier on the diamonds than IGI/GCAL!

Every lab diamond we have submitted so far received an Ideal 0 grade (for those not familiar with AGS cut grading, they grade from 0-10 with 0 being the best grade).

Here is side-by-side grading comparison of a few lab diamonds. (Mods- please note this is *not* a sales post - my intent is to share a unique chance to look at secondary grading of man made diamonds with the PS community)


If you believe everything you read on the internet, you may believe that IGI and GCAL provide liberal/loose grades. 'Experts' may have convinced you that an F color graded by IGI is actually an H color if graded by AGS, or a VS2 graded by IGI/GCAL should be considered a SI1 or SI2. Our results directly contradict this.

There's a few reasons the conventional wisdom proved to be wrong in our experience so far:
  1. Four C's grading of diamonds is not that complicated. IGI and GCAL employ gemologists who are trained and certified by GIA, and those experts aren't actually far off from experts in other grading labs in terms of their assessment of high quality diamonds. They use the same equipment and same techniques to grade diamonds. IMHO, human graders will mostly disappear in the next decade, as AI powered machines are increasingly being used to grade diamonds.
  2. Cynics might say, the grading labs have been harmed financially by the pandemic and need new business to continue operations. Providing diamonds with liberal grades increases the chances of future business, regardless of whether its lab or mined.
  3. We didn't submit low-quality lab diamonds for grading. The worse the color and clarity the more likely you'll have grading disparities between labs because the diamonds themselves can vary so much in terms of quality. There is a lot more subjectivity in an I-J-K color than a D-E-F color grade.
  4. In natural diamonds, high-quality diamonds are rarely graded by IGI or GCAL, where as IGI and GCAL have graded virtually all lab diamonds.
Want a lab diamond graded by AGS or GIA? Unfortunately, it will be a while before AGS and GIA graded lab diamonds are widely available, as both laboratories are just ramping up their grading of lab diamonds now, and most wholesalers of lab diamonds are taking a wait-and-see approach to demand for AGS/GIA grades as they are more expensive than IGI/GCAL grading. Don't be surprised if it takes eCommerce web sites a longer time to regularly offer AGS and GIA, particularly on diamonds that have previously assigned IGI and GCAL certs.

If you do find a diamond that you love, but want the assurance of a grade by GIA or AGS, your jeweler should be able to submit the diamond for secondary grading and lead times are running about 6-10 business days right now.
 

AprilBaby

Super_Ideal_Rock
Premium
Joined
Jul 17, 2008
Messages
11,434
Thanks! That makes me feel good about my grading!
 

diamondseeker2006

Super_Ideal_Rock
Premium
Joined
Jan 11, 2006
Messages
56,278
We were invited to participate in the pilot phase of AGS's return to grading lab diamonds, and we have the results back from our first few batches graded by AGS. Most of the stones we sent were previously graded by IGI or GCAL so I am sharing the results with the community to address the 'conventional wisdom' about IGI grading.

The vast majority of diamonds we submitted to AGS for secondary grading received the same color and clarity grades as their first grading. When AGS differed from IGI or GCAL, the results were only off by one (E vs F color, VS1 vs VS2). More often than not, AGS was looser/easier on the diamonds than IGI/GCAL!

Every lab diamond we have submitted so far received an Ideal 0 grade (for those not familiar with AGS cut grading, they grade from 0-10 with 0 being the best grade).

Here is side-by-side grading comparison of a few lab diamonds. (Mods- please note this is *not* a sales post - my intent is to share a unique chance to look at secondary grading of man made diamonds with the PS community)


If you believe everything you read on the internet, you may believe that IGI and GCAL provide liberal/loose grades. 'Experts' may have convinced you that an F color graded by IGI is actually an H color if graded by AGS, or a VS2 graded by IGI/GCAL should be considered a SI1 or SI2. Our results directly contradict this.

There's a few reasons the conventional wisdom proved to be wrong in our experience so far:
  1. Four C's grading of diamonds is not that complicated. IGI and GCAL employ gemologists who are trained and certified by GIA, and those experts aren't actually far off from experts in other grading labs in terms of their assessment of high quality diamonds. They use the same equipment and same techniques to grade diamonds. IMHO, human graders will mostly disappear in the next decade, as AI powered machines are increasingly being used to grade diamonds.
  2. Cynics might say, the grading labs have been harmed financially by the pandemic and need new business to continue operations. Providing diamonds with liberal grades increases the chances of future business, regardless of whether its lab or mined.
  3. We didn't submit low-quality lab diamonds for grading. The worse the color and clarity the more likely you'll have grading disparities between labs because the diamonds themselves can vary so much in terms of quality. There is a lot more subjectivity in an I-J-K color than a D-E-F color grade.
  4. In natural diamonds, high-quality diamonds are rarely graded by IGI or GCAL, where as IGI and GCAL have graded virtually all lab diamonds.
Want a lab diamond graded by AGS or GIA? Unfortunately, it will be a while before AGS and GIA graded lab diamonds are widely available, as both laboratories are just ramping up their grading of lab diamonds now, and most wholesalers of lab diamonds are taking a wait-and-see approach to demand for AGS/GIA grades as they are more expensive than IGI/GCAL grading. Don't be surprised if it takes eCommerce web sites a longer time to regularly offer AGS and GIA, particularly on diamonds that have previously assigned IGI and GCAL certs.

If you do find a diamond that you love, but want the assurance of a grade by GIA or AGS, your jeweler should be able to submit the diamond for secondary grading and lead times are running about 6-10 business days right now.
Jason, this is good news! I personally wouldn't care to add to the price to have more expensive grading as long as the IGI and GCAL are accurate.

I did want to mention one thing. I am only casually exploring lab diamonds at the moment. I might buy if I found exactly what I wanted at a good price, although I am concerned about the internal graining I keep reading about. But I went to your site and you don't list your diamonds. I am not going to provide my name and email address in order to have a sales rep contact me. I know I am at least as qualified as they are to pick out a diamond, so I prefer to choose one without a sales person until I am ready to buy the stone. I think this is going to be a disadvantage for you, because most PS members are just going to use Rare Carat to sift through the lab diamonds. I don't mind going to sites that are not on Rare Carat, but I won't bother with it if the diamonds aren't listed.
 

missy

Super_Ideal_Rock
Premium
Joined
Jun 8, 2008
Messages
41,887
The vast majority of diamonds we submitted to AGS for secondary grading received the same color and clarity grades as their first grading. When AGS differed from IGI or GCAL, the results were only off by one (E vs F color, VS1 vs VS2). More often than not, AGS was looser/easier on the diamonds than IGI/GCAL!
Very interesting. Thanks for sharing.

I’m with @diamondseeker2006 as long as the labs are accurate there’s no need to add to the cost.
 

free-user

Rough_Rock
Joined
Sep 17, 2020
Messages
82
This needs more attention. Good job ada diamonds. I cannot wait for more members of the grading family to expand to lab diamonds. Im one that's waiting for ags to come out with more grading output of lab diamonds. I plan on upgrading! I'm curious though how many were submitted?
 

123ducklings

Brilliant_Rock
Joined
Jun 10, 2020
Messages
537
If you believe everything you read on the internet, you may believe that IGI and GCAL provide liberal/loose grades. 'Experts' may have convinced you that an F color graded by IGI is actually an H color if graded by AGS, or a VS2 graded by IGI/GCAL should be considered a SI1 or SI2. Our results directly contradict this.

...

We didn't submit low-quality lab diamonds for grading. The worse the color and clarity the more likely you'll have grading disparities between labs because the diamonds themselves can vary so much in terms of quality. There is a lot more subjectivity in an I-J-K color than a D-E-F color grade.
Thank you for posting. I am one who is wary of IGI and GCAL, and while it’s interesting I’m not sure this info helps me much as a consumer. I wish we had some comparison data on G-K stones from IGI or GCAL. As you say, there seems to be greater discrepancy with those stones. In omitting them are you not therefore skewing the results to show an inaccurate level of consistency across labs?

For me, the visual difference between E and F is negligible. I am happy to buy an MMD reported to be E and receive a stone that performs as an F. However the difference between H and K is significant. If I buy an MMD reported as H, I want to receive a stone that performs close to that. And what I’ve been seeing both anecdotally from customers and in vendor videos are MMD that are graded near colorless by the softer labs but look much warmer.

It’s going to take much more information for me to trust an IGI or GCAL near colorless grade.
 

Ada Diamonds CEO

Rough_Rock
Trade
Joined
Jan 8, 2020
Messages
69
In omitting them are you not therefore skewing the results to show an inaccurate level of consistency across labs?

For me, the visual difference between E and F is negligible. I am happy to buy an MMD reported to be E and receive a stone that performs as an F. However the difference between H and K is significant. If I buy an MMD reported as H, I want to receive a stone that performs close to that. And what I’ve been seeing both anecdotally from customers and in vendor videos are MMD that are graded near colorless by the softer labs but look much warmer.
Over 90% of what we sell is DEF, and we only sell G and H colors from a small minority of CVD growers that can produce more natural, warm diamonds. Thus I don't have any H-K color diamonds to send for secondary grading.

If anyone else has secondary grading info from GIA or AGS, I'd love to know your results!

____

Most of the near-colorless CVD goods are an unnatural brown color palette as the sources of the color in CVD are completely different than the sources in natural diamonds.

Thus, the typical H color CVD diamond will be far less appealing than the typical H color natural diamond. IMHO of course!
 
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