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Help - could GIA have made a big error with the measurements of my cushion?

diamondhoarder

Brilliant_Rock
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Hi PS'ers :wavey:

I am in the process of buying this newly cut/ newly certified step cut cushion.

20190901_142720.jpg

Here is the ASET:

20190901_142646.jpg

Looks pretty "square" right?

According to the GIA cert dated 1st August 2019, it is a slightly elongated shape with length: 6.84mm x width: 5.66mm x depth: 3.75mm. This gives a ratio of 1.2 !?!?! which can definately look rectangular (I know because I have an EC with this ratio) But the images do not suggest an elongated shape at all. :confused::confused::confused::confused::confused:

I thought that maybe the wrong images had been paired with the wrong GIA cert, but when I looked at highly magnified images of the stone from the side view I could that the GIA number lasered onto the girdle matches the number on the GIA cert, so apparently the images and the certificate or both the same stone.

How can this be? Is there an optical illusion going on here? :think:

I have heard that AGS measures some squarer fancy shapes from corner to corner as one of their dimensions (which would give a bigger measurement than length or width) but according to the GIA website this is how GIA measure:

"MEASUREMENTS:

Described in millimeters to two decimal places, a diamond’s dimensions are listed as “minimum diameter – maximum diameter x depth” for round diamonds and “length x width x depth” for fancy-shaped diamonds."

The vendor doesn't have the diamond in hand so they can't check the diamond's measurements themselves unless I purchase it.

Is it possible that GIA have made a mistake with the measurements of this stone????

Also the diamond is 1.01cts, wouldn't it face up rather large for its size if these dimensions are correct?

Anyone who sees an elongated shape in these images or who has experience of GIA grading of fancies, please let me know your thoughts!
 

ecf8503

Ideal_Rock
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Like Brian Gavin's cushions, I suspect the longer dimension is on the diagonal.
 

diamondhoarder

Brilliant_Rock
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Like Brian Gavin's cushions, I suspect the longer dimension is on the diagonal.
Are Brian Gavins cushions GIA certed then? Or AGS? I know that AGS does it that way but I didnt think GIA does. But it would make sense of the dimensions in this case
 

diamondhoarder

Brilliant_Rock
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Ditto...that's what I was thinking.

EDIT...BGD cushions are AGS.

Has anyone ever heard of GIA doing it that way?

Also, just to confuse things further, the plot diagram on the cert shows an elongated cushion shape?!?

20190901_161615.jpg
 

PreRaphaelite

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It *is* possible for them to make mistakes. I contacted them in a hurry when they had my stone and got the description wrong. They corrected their mistake in the report. If you’re concerned, contact them and ask for a review.
 

diamondhoarder

Brilliant_Rock
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It *is* possible for them to make mistakes. I contacted them in a hurry when they had my stone and got the description wrong. They corrected their mistake in the report. If you’re concerned, contact them and ask for a review.

So does everybody agree that this diamond cannot have length 6.84mm x width 5.66mm based on these images? Or Does anyone see a slightly elongated cushion in these images?
 

PreRaphaelite

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It does seem to be a mistake on their part.... but I have learned that my eyes are not as reliable as they once were. What do other PSers eyes say?
 

Venzen007

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To me, the ASET image appears just off square, seemingly slightly more tall than wide, but maybe in terms of a 1.02, not a 1.2!
 

diamondhoarder

Brilliant_Rock
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To me, the ASET image appears just off square, seemingly slightly more tall than wide, but maybe in terms of a 1.02, not a 1.2!
Yes, that was my thought too. I feel like its all a bit misleading as if the 6.84mm measurement is the diagonal and not the length I'm going to end up with a smaller stone than advertised and be disappointed!
 

Wewechew

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Is it my imagination that the bottom left corner in the top pic is rounded a bit more than the others? In the second pic it’s the right bottom corner.
 

Rose-gold-or-bust

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It gives a ratio of 1:1.2 which is very close to 1:1 square. 1:2 would be a rectangle that is twice the length on one side than the other. It is only 1.18mm longer on one side than the other which isn’t going to make it look elongated to most people
 

diamondhoarder

Brilliant_Rock
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Is it my imagination that the bottom left corner in the top pic is rounded a bit more than the others? In the second pic it’s the right bottom corner.

I think you might be right! I'm wondering if that is contributing to an optical illusion of squareness
 

diamondhoarder

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It gives a ratio of 1:1.2 which is very close to 1:1 square. 1:2 would be a rectangle that is twice the length on one side than the other. It is only 1.18mm longer on one side than the other which isn’t going to make it look elongated to most people

This is what the vendor said to me when I queried it. But then I got my ruler and measured the dimensions of the image on my monitor. When I use these measurements I can get a 1.1.03 ratio at best, not 1:1.2. But that assumes that the face-on image is not distorted by being at an angle for the photography or something. It doesnt look like it to me, but I have looked at it so many times I'm starting to doubt myself! :lol-2::wall:
 

Rose-gold-or-bust

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It gives a ratio of 1:1.2 which is very close to 1:1 square. 1:2 would be a rectangle that is twice the length on one side than the other.
This is what the vendor said to me when I queried it. But then I got my ruler and measured the dimensions of the image on my monitor. When I use these measurements I can get a 1.1.03 ratio at best, not 1:1.2. But that assumes that the face-on image is not distorted by being at an angle for the photography or something. It doesnt look like it to me, but I have looked at it so many times I'm starting to doubt myself! :lol-2::wall:


You really can’t measure from a photo. If the diamond want perfectly head on, it would be distorted. Cameras lenses all have slight distortion as well we monitors.
 

OcnGypZ

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The measurements are l x w. Not Diagonal. If stone were 5.66 x 5.66 the diagonal would measure 8.
 

diamondhoarder

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The measurements are l x w. Not Diagonal. If stone were 5.66 x 5.66 the diagonal would measure 8.

Did you calculate this taking into account that the corners are rounded not squared?

I get 8mm for a true square, but where the corners are rounded I feel like it would be closer to 7 (or 6.88 even) But I also really want to be wrong because I want the diamond to face up larger with 6.88 being the long side not the diagonal.
 

oldminer

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AGS definitely has used the diagonal on some cushion shaped diamonds on reports. The ones I have seen were certain Branded cushion cuts, not generic ones. It seems that vendors are able to negotiate this modification from Length x Width x Depth measurements into Minimum Width x Maximum Width x Depth. I have voiced my concern over the years to people in the trade, but I understand the competitive advantage of reporting the measurements in this way, in spite of the mis-leading nature of handling it secretly unless someone notices. Maybe GIA has reason enough to report the measurements this way, too, or possibly it is an operational error with the scanner. Every scanner always detects the minimum and maximum widths. It also can detect the correct length and width of particular assigned shapes. An incorrect choice of "shape" or "outline" on the part of the operator can make this error import to their Cert software. Just like getting a lucky color or clarity grade, a lucky error in measurement might not even be noticed by a seller or might easily be noticed in hopes no one will question it.

The diamond in the image you provided is not 1:1.2 length to width ratio. 1.2 is 20% longer in length than width and your photo does not look like that. If the 1:1.2 refers to minimum width to diagonal length ratio, then maybe we have the answer. On my screen I get about 14.5cm width x app 17.3cm. That 1:1.186 which is darn close to the 1:1.2.
 

Swirl68

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Looking up other cushion certificates in the 1.00-1.01 carat range, it looks like that 6 should probably be a 5.
 

Rose-gold-or-bust

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Did you calculate this taking into account that the corners are rounded not squared?

I get 8mm for a true square, but where the corners are rounded I feel like it would be closer to 7 (or 6.88 even) But I also really want to be wrong because I want the diamond to face up larger with 6.88 being the long side not the diagonal.


6.88 is the long side. I am not sure how else to explain it. It looks square because the difference between the two sides is so slight that you can’t easily perceive it with your eyes. The rounding of the corners helps this. If you have a mm grid paper, draw it out to scale. You are not looking at a truly square stone
 

John P

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A diamond with those measurements would need to be tilted off-axis by at least 30 degrees to appear square in the top two photos.

Two possibilities –

1. GIA’s measurements are wrong.
2. The top two photos show a different diamond.

I suggest you chase #2 first.

The vendor doesn't have the diamond in hand so they can't check the diamond's measurements themselves unless I purchase it.
Someone has the diamond in hand and I presume they want to sell it. You have a valid question/concern which needs a logical answer: If GIA’s measurements are wrong the sale could be compromised. If the top two photos show a different diamond the sale could be compromised. If there is a third possibility let them bring it forward. Your vendor knows who is providing the photos and can chase this for you.
 

diamondhoarder

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A diamond with those measurements would need to be tilted off-axis by at least 30 degrees to appear square in the top two photos.

Two possibilities –

1. GIA’s measurements are wrong.
2. The top two photos show a different diamond.

I suggest you chase #2 first.


Someone has the diamond in hand and I presume they want to sell it. You have a valid question/concern which needs a logical answer: If GIA’s measurements are wrong the sale could be compromised. If the top two photos show a different diamond the sale could be compromised. If there is a third possibility let them bring it forward. Your vendor knows who is providing the photos and can chase this for you.

Hi John

Thanks for your input. I managed to find the GIA laser inscription on the video of this stone and it matches the number on the cert. The photo also matches the video when the diamond is face on. So I can only now assume that GIA made an error, and I would be getting a smaller looking stone that I was expecting. I will go back to the vendor and flag up my concerns.
 

oldminer

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A "typo" is when you use an incorrect key or two, skip a letter, or transpose characters when typing text. An "error" is when you have a drop down menu, choose the incorrect word and fail to proof read the output before sending it to be printed. Admitting to making an error is no big deal unless it implies you casually accept that the quality control of your output is flawed. Every GIA report should simply have a digitally measured strength and color of fluorescence box. Using words when exact measurements are readily obtained leads to needless and repeated errors on reports. High time to improve that area on diamond reports.
 

PreRaphaelite

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It would be helpful to decimalize (is that a reasonable word?) fluorescence on a scale of 1-10, instead of using adjectives, just as you say @oldminer
 

denverappraiser

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6.84mm x width: 5.66mm would be noticeably oval.
Whoever has the stone can directly measure it. I suspect the photos are not of the correct diamond.
GIA uses l x w, not corner to corner on cushions.
 

diamondhoarder

Brilliant_Rock
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Thanks for all the input on this everyone. The vendor was only prepared to call this stone in and examine the issues further if I purchase it first. So I decided not to go ahead. Its annoying but I did also have concerns about possible darkness under the table based on the ASET so these issues with the measurements have helped me to decide to walk away from the stone - too many possible issues.
 
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