Find your diamond
Find your jewelry
shape
carat
color
clarity

GIA tricked & cheated: +63% depth XXX diamonds

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,823

A cut grade of Excellent from the Gemological Institute of America (GIA) is a target many diamond manufacturers are eager to reach. Recently, some of them have gotten creative in their efforts to achieve that goal — a bit too creative, critics say.

Personally, I think GIA's excuse is pathetic.
 

kenny

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
27,461
Garry, that link requires a log in.

Are you allowed to post the article's text, or a summary in your own words?
 
Last edited:

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,823
Oops,
"Round brilliants have started turning up with extra facets where the girdle meets the “pavilion main” facet, which runs down to the bottom tip of the diamond. Polishers appear to have made these tiny adjustments to take advantage of the GIA’s method of scoring a stone’s cut quality. "

GIA claimed in the article that their method of calculating depth % for their X cut grade system was to add the crown height, girdle thickness at the thickest point plus the depth of pavilion. DoH, what is wrong with average diameter divided into the depth in mm's as infact everyone does, including them as in the number they print on their report. Dumb as!

"Full disclosure

One of the most vocal critics of this practice is Garry Holloway, a diamond retailer in Melbourne, Australia. A geologist by education, Holloway has long studied diamond cuts and has created an online program for assessing cut quality. The case of the extra facets was the subject of a YouTube video he put out in August, explaining how a stone with 64.9% depth was able to achieve an Excellent grade.

Holloway believes the GIA has a responsibility to alert the public to this phenomenon by publicizing the certificate numbers of the relevant stones and posting a notice on its website. “The GIA should name and shame the companies that produced these cheated-girdle diamonds,” he declares in an interview with Rapaport Magazine."
Think it is OK for me to quote bit about me?
I alerted Rapaport mag to the issue based on this video of a diamond that I have posted here on PS RT before:

1576107408290.png
 

kenny

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
27,461
Garry, kudos to your for exposing this fraud!

I have deep respect for your life's work.
From where I sit I'd say your tools have resulted in many of us enjoying fantastic light performance from diamonds that previously previously were nearly always cut for weight only.

Thank you!!!
 
Last edited:

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,823
I am a bit busy, but I had a quick look and there are plenty of 63.9% XXX rounds listed on PS (63% is meant to be the cut off.
This one https://www.b2cjewels.com/dd/12327320/round-diamond-F-color-SI1-Clarity?sku=12327320&utm_source=pricescope.com&utm_medium=referral&utm_campaign=pricescope.com
has a video and I can not see any extra facets under the girdle.
Not that extra facets were even noted correctly on the stone in my video. The extra facets are at facet junctions. So maybe there is some bribery or something else going on as this really beggars belief?
1576119992692.png

Also note that GIA claim this started early this year and to claim to now be calling these stones modified Brilliants with no cut grade. They also claim to have fixed the problem (I think in August) but this stone is 10 days old!
1576119776889.png
 

TODiamonds

Shiny_Rock
Joined
Jul 27, 2019
Messages
260
I've seen tons of 63% XXX's which was already ridiculous to begin with. 64%+ is unreal.

GIA is pathetic. Wish they would muster some balls...
 
  • Like
Reactions: JrJ

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
8,939
Why does this 65 faceted diamond still get graded as a MRB by GIA?
The are small enough to be listed as extra facets which are allowed without penalty.
The principle was that if a meet point was missed slightly they could cut a small facet to cover it up and get EX symmetry.
They were common in the past and still show up occasionally, mostly on fancies with modern production processes.
So you might say that GIA got kicked in the teeth for allowing some leeway in the past by these #%@%#@%@ cutting these.
GIA shares the blame for not doing enough about it.
 
Last edited:

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
8,026
HI All! I have received permission from Rappaport to re-print the article here, in its entirety. I needed to include a link at the bottom- but it likely won't work for non Rap members.
COVER
Trick of the trade

Cutters have been trying to ‘cheat’ the GIA into giving diamonds Excellent cut grades by sneaking in extra facets.

By Joshua Freedman
“Republished with permission of Rapaport. © Rapaport USA, Inc. All rights reserved.”



A cut grade of Excellent from the Gemological Institute of America (GIA) is a target many diamond manufacturers are eager to reach. Recently, some of them have gotten creative in their efforts to achieve that goal — a bit too creative, critics say.

Round brilliants have started turning up with extra facets where the girdle meets the “pavilion main” facet, which runs down to the bottom tip of the diamond. Polishers appear to have made these tiny adjustments to take advantage of the GIA’s method of scoring a stone’s cut quality.

“We began seeing stones with multiple extra facets at the pavilion main/girdle junction earlier in 2019,” says Phil Yantzer, the GIA’s vice president of US laboratory operations. “These extra facets may be able to impact the measured girdle thickness that is used in part to determine the GIA cut grade.”

Depth perception

The GIA calculates a brilliant-cut diamond’s depth by adding together the height of the crown, the average thickness of the girdle and the depth of the pavilion. It expresses this as a percentage of the stone’s diameter, with 63% being the maximum permitted depth for an Excellent cut. A diamond that is too deep reflects light badly and can appear small, while a disproportionately thick girdle can look ugly and squander valuable weight on a part of the stone most people don’t see.

However, the GIA faces a problem when there’s an extra facet at the junction of the girdle and the pavilion. In addition to making the girdle thinner, that small feature reduces the length of the pavilion main, which is the plane the GIA uses to measure pavilion depth, explains Shimon Gerstensang of the Rapaport Group’s trading department.

“This extra facet is not a part of the girdle, is not a part of the crown, and is not a part of the pavilion,” he says.

In other words, the top-to-bottom distance of the extra facets gets “lost” when the GIA calculates the total diamond depth. This creates the possibility that diamonds will get a lower depth percentage than they deserve, potentially inflating their cut grade.

Full disclosure

One of the most vocal critics of this practice is Garry Holloway, a diamond retailer in Melbourne, Australia. A geologist by education, Holloway has long studied diamond cuts and has created an online program for assessing cut quality. The case of the extra facets was the subject of a YouTube video he put out in August, explaining how a stone with 64.9% depth was able to achieve an Excellent grade.

Holloway believes the GIA has a responsibility to alert the public to this phenomenon by publicizing the certificate numbers of the relevant stones and posting a notice on its website. “The GIA should name and shame the companies that produced these cheated-girdle diamonds,” he declares in an interview with Rapaport Magazine.

Rounding off

For its part, when the GIA became aware of the practice, it began classifying the stones as “round modified brilliant” rather than simply “round brilliant.” This put them out of reach of a cut grade, which the GIA only assigns to the standard shape. In addition, it adjusted its instrumentation to prevent the extra facets from affecting the grade, and invited clients to resubmit stones that had come back as round modified brilliant.

Yantzer won’t speculate on whether any diamonds with an incorrect cut grade have already reached the market. Asked whether the laboratory should publish a warning, he says there is no way to identify which diamonds may have received an inflated score.

Number-rounding can sometimes be responsible for legitimate mismatches between the “measured” depth that appears on a grading report (the distance from table to culet) and the “calculated” depth the lab uses to determine the cut grade, the GIA adds. As a result, diamonds with a measured depth exceeding 63% can sometimes correctly receive an Excellent cut grade because the calculated depth came out lower, according to Yantzer.

Responsible selling

That said, the fact that there are around 37,000 diamonds on RapNet with a depth ranging from 63.1% to 65% and an Excellent GIA cut grade has prompted some, like Holloway, to voice concern.

Irrespective of what appears on a GIA report, sellers need to show responsibility for what they sell, argues Saville Stern, RapNet’s chief operating officer.

“Diamantaires add value due to their experience and knowledge, and they should not ignore this in the face of a grading report,” he says.

The girdle hurdleThe standard brilliant cut, developed by Marcel Tolkowsky in 1919, contains 57 facets (excluding the culet). The cutter will start by forming eight facets on the pavilion — the lower part of the diamond — and eight on the crown. Seen from the bottom of the diamond, the pavilion will resemble an eight-slice pizza. For some smaller diamonds, the manufacturer will stop adding facets at that point, leaving what traders call an “8/8” or single-cut diamond.

Because the rough has a rounded, spinning-top shape, putting flat facets on the crown and pavilion results in a curved edge where the wider end meets the girdle, like the rounded crust of a pizza slice. (The same thing happens if you sharpen a pencil with a knife.) As a result, the borders of the girdle are wavy, with thinner and thicker parts.

On most diamonds, the polisher will cut an inverted “v” (as viewed from the side) into all of those eight pavilion facets to turn them each into three facets: two triangular ones and another with a kite shape. The kite-shaped facet, which now only touches the girdle at one point, is called the “pavilion main.” The other two are “half facets,” and like the original eight pavilion facets, they will have a curved border with the girdle. So will the new facets the cutter makes on the crown. This doubles the number of waves on the girdle, making its depth even less consistent along its length.

Since the GIA needs to quantify that depth somehow, it has chosen to assess it at its thinnest points when determining girdle thickness for grading reports, with “slightly thick” being the maximum the GIA permits for an Excellent cut. However, when calculating a diamond’s overall depth, the lab measures the girdle at its thickest points and adds that number — expressed as a percentage of the diameter — to the depth of the crown and the pavilion. That’s why manufacturers looking to maximize their cut grade have focused on the thick spots of the girdle where it meets the pavilion main.
Image: Rapaport
Article from the Rapaport Magazine - December 2019. To subscribe click here.
“(To read the original article, please click here)”
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,823
@Garry H (Cut Nut)
It is important to add that GIA had changed girdle thickness measurements since August 2019.
Screenshot 2019-12-12 09.28.47.png Screenshot 2019-12-12 09.29.00.png
Sergey how do you account for the fat that GIA are still issuing certs for +63% stones when their own Facetware software would ding this 11 day old cert?
(If I drop the girdle to 3.5% as stated on the cert then it scores Excellent, but the depth % is then at 63%). I am confused. Even accounting for possible rounding errors the stone is still 63.9% depth which is a fact.
1576194082416.png

Glad you got the full article David.
Note the strange comments from GIA as to how they arrive at a depth %. Of course it is dumb, but also runs foul of their own rules:
Total depth percent should be used only when girdle thickness percent is not available. When total depth percent is used in calculations, Facetware® will “estimate” the girdle thickness percent from the other data available and produce less accurate results."
 

TODiamonds

Shiny_Rock
Joined
Jul 27, 2019
Messages
260
This just reeks of blatant manipulation. How GIA turned a blind eye to this is beyond me...

Perhaps if GIA continues letting shit like this slide, it will erode their credibility to the point where an opportunity may open up for one of the second tier global players like IGI to take market share.
 
Last edited:

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,470
Sergey how do you account for the fat that GIA are still issuing certs for +63% stones when their own Facetware software would ding this 11 day old cert?
(If I drop the girdle to 3.5% as stated on the cert then it scores Excellent, but the depth % is then at 63%). I am confused. Even accounting for possible rounding errors the stone is still 63.9% depth which is a fact.
1576194082416.png

Glad you got the full article David.
Note the strange comments from GIA as to how they arrive at a depth %. Of course it is dumb, but also runs foul of their own rules:
Total depth percent should be used only when girdle thickness percent is not available. When total depth percent is used in calculations, Facetware® will “estimate” the girdle thickness percent from the other data available and produce less accurate results."
@Garry H (Cut Nut)
please publish the 11 day old GIA grading report with 63.5% and EX grade. You published 11 months old report.
Seems you did not understand the reason of problem. Please call me or Janak before you continue mislead consumers on PS.
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,470
@Garry H (Cut Nut)
please publish the 11 day old GIA grading report with 63.5% and EX grade. You published 11 months old report.
Seems you did not understand the reason of problem. Please call me or Janak before you continue mislead consumers on PS.
@Garry H (Cut Nut) @Karl_K
sorry for misprint.
I asked a modern GIA grading report like 1st sample had been published by Garry with 64.9%( or any modern GIA report with 64.5%+ total Height and EX grade)

I do not see any problem with extra facets and girdle thickness in sample 1345193357 Dec. 2, 2019
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,823
@Garry H (Cut Nut) @Karl_K
sorry for misprint.
I asked a modern GIA grading report like 1st sample had been published by Garry with 64.9%( or any modern GIA report with 64.5%+ total Height and EX grade)

I do not see any problem with extra facets and girdle thickness in sample 1345193357 Dec. 2, 2019
I did mention in an earlier post Sergey that one of the 3 stones i found had a video and I could not see any extra facets - yet these stones are still deeper than 63% which GIA have always claimed to be a magic cut quality downgrade number (which as we know is silly because spread per carat weight is more useful information.
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,470
Oops, sorry, I pasted the wrong stone Sergey.
Try this - same story: (edited to add that the avg diamter is 6.315 divided into 4.04 = 6.397466 which if the other nunbers were rounded up may not mean that that this stone is 64% depth???)
1576219069043.png
Garry, it is not a same story. I do not see a connection between the sample and extra facets for girdle thickness reduction . You mixed 2 very different issues and it is very misleading
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,470
I did mention in an earlier post Sergey that one of the 3 stones i found had a video and I could not see any extra facets - yet these stones are still deeper than 63% which GIA have always claimed to be a magic cut quality downgrade number (which as we know is silly because spread per carat weight is more useful information.
1) Sorry, I do know anything about such GIA claim . Could you please give a link to such GIA statement? For my understanding GIA does not use a total height to grade cut quality .
2) I am disagree with approach that a diamond with low spread has to receive less cut quality grade just because it has less spread. A spread value is important for price( discounts) only.( it is like mass)
Now 2 diamonds with identical proportions and different mass's ( for example 0.9ct and 1ct) have same cut grade. Same has to be for 2 diamonds with identical optical performance and different spread values, they have to receive same cut grade.

if a spread will change cut grade then many very nice fancy cuts will never receive EX grades.
Please take for example perfect RBC then increase girdle thickness. It will change a spread but a performance will same. A consumer needs information about Optical performance and spread separately to select a diamonds with high performance and ask discount for negative spread .
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
8,939
It looks like just plain old cwappy GIA rounding will allow a stone to get rounded 63 in facetware and EX while the stone is physically over 64%. Putting the numbers in DC also comes out as 63.3% depth.
results.jpg Image 2.jpg
 

Attachments

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,470
It looks like just plain old cwappy GIA rounding will allow a stone to get rounded 63 in facetware and EX while the stone is physically over 64%. Putting the numbers in DC also comes out as 63.3% depth.
results.jpg Image 2.jpg

In the grading report the culet size is None. In facetware you used VSM. Even for culet None Facetware uses 0.5%, it creates a difference in Pavilion height calculations.
for Pavilion angle 41.2 Pavilion height 43.77%( rounded to 44% in a report)
in Facetware Pavilion height for same Pavilion angle is 43.6 because a culet is 0.5%. it is explain 0.4% from 0.7% difference in Total height 's

and again it has not any connection with the Garry article
 

sledge

Ideal_Rock
Premium
Joined
Apr 23, 2018
Messages
4,354
In the grading report the culet size is None. In facetware you used VSM. Even for culet None Facetware uses 0.5%, it creates a difference in Pavilion height calculations.
for Pavilion angle 41.2 Pavilion height 43.77%( rounded to 44% in a report)
in Facetware Pavilion height for same Pavilion angle is 43.6 because a culet is 0.5%. it is explain 0.4% from 0.7% difference in Total height 's

and again it has not any connection with the Garry article
Updated Facetware using None culet.

Pavilion reduced to 43.6% as you said.

But overall depth still reducing to 63% and assigning estimated cut grade of EX.

Screenshot_20191213-062442_GIA Facetware.jpg
Screenshot_20191213-062448_GIA Facetware.jpg
Screenshot_20191213-062455_GIA Facetware.jpg
 
Last edited:
Be a part of the community It's free, join today!

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.
Top