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Lets talk about leakage (to the naked eye)

cj2be

Shiny_Rock
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Mar 14, 2019
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Hi! I want to learn more about how to spot leakage in a diamond with my naked eye, specifically in diamonds labeled GIA XXX but have uncomplimentary angles (like 35/41 or 33/40.6). I’m not referring to the diamonds that are clearly out of ideal range with pavilions exceeding 41.2 but the ones that labs label as “ideal” cuts when they really aren’t ideal in the sense it is used on this forum. I know idealscopes and ASET images are the go to, but is it possible to spot leakage in such diamonds to the naked eye?
 
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flyingpig

Ideal_Rock
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First, generally, 33/40.6 is rather unlikely to have detectable light leakage. A well cut 35/41 may not have detectable light leakage.
Regardless of what the angles are if there is light leakage, it can be detected with naked eyes with no tool and magnification.

Here are the steps.

Newbie: does not know how to interpret IS and ASET

New PS member: recognize and differentiate between good and bad ID/ASET. But cannot make connection with actual photo or video

Regular PS member: can reasonably predict what the IS/ASET will look like just based on video or actual photo without report or proportion information. Knows how all performance images translate IRL performance

Expert PS member: can do what regular PS member can without magnification or special tool. Can reasonably predict table%, PA, CA. Can even detect painting and digging. Spotting leakage is easy

To answer your question, yes you can, eventually.
 

Karl_K

Ideal_Rock
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In a combination that is predicted to have just the typical leakage you look between the arrow shafts under the table and look for variation.
If one or 2 areas stand out rotate the stone and compare again.
If the same areas are again different there is a good chance they are different and further investigation is needed.
There are stones on the market with twist in the pavilion that will stand out like a sore thumb using this test.
But be careful once you start training your eye you will never look at a diamond the same way again.
 

flyingpig

Ideal_Rock
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Looks like there’s some leakage at 6 and 7 o’clock and something is going on at 11 as well. Right?
Clear leakage and twisted pavilion between 730 and 9 o'clock arrows. Between 6 and 730 is a tough call.
11 oclock is actually fine.
 
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gm89uk

Brilliant_Rock
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Teach me your magic! How do you see leakage this way?
The twisted LGF mains show up as obstruction where there shouldn't be, those two triangles between the arrows. Under the table in that section you can see the colour compared to the edge of the diamond is darker and mushy. As the diamond rotates slightly, there is dispersion and activity under the rest of the table apart from this section which remains dead and inactive. Between half 6 and 7 I'd say has partial leakage.

At 11 o'clock is just normal obstruction from a lower girdle facet (half pavilion mains)
 

cj2be

Shiny_Rock
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148
Clear leakage and twisted pavilion between 730 and 9 o'clock arrows. Between 6 and 730 is a tough call.
11 oclock is actually fine.
I guess what I’m looking at is right before 12. It looks like a reflection of an arrow? What is that?
 

lovedogs

Ideal_Rock
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The twisted LGF mains show up as obstruction where there shouldn't be, those two triangles between the arrows. Under the table in that section you can see the colour compared to the edge of the diamond is darker and mushy. As the diamond rotates slightly, there is dispersion and activity under the rest of the table apart from this section which remains dead and inactive. Between half 6 and 7 I'd say has partial leakage.

At 11 o'clock is just normal obstruction from a lower girdle facet (half pavilion mains)
This? Annotation 2020-01-22 140359.png
 

cj2be

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62748AD1-EC1F-4D43-A481-C6C54DF35885.jpeg 50B20021-5238-4D48-AC5A-3D3DF3EC4572.jpeg
Here’s a couple from off the web. The first has the 34/41 combo and the second has 36/40.6. Are those dark areas leakage?
 

flyingpig

Ideal_Rock
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N
62748AD1-EC1F-4D43-A481-C6C54DF35885.jpeg 50B20021-5238-4D48-AC5A-3D3DF3EC4572.jpeg
Here’s a couple from off the web. The first has the 34/41 combo and the second has 36/40.6. Are those dark areas leakage?
Leakage (in these photos and JA videos) does not appear dark or black. If you see darkness, it is either reflection of the black camera or something dark in the room where the image is taken.
Instead, leakage appears mushy, glassy and watery, and will show the stone color if H or lower.
See @tyty333 response. It is easier to start with cushion. That is how I learned. MRB is a bit harder.

About the two new photos, the first stone is cut very evenly. The lighting setting is not the best to evaluate brilliance and leakage.. The second one may have wonky pavilion in one area just like the JA stone I linked earlier. Would like to see the videos.
 

flyingpig

Ideal_Rock
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20200122_233853.jpg
Red are the black triangles between the arrows, that are obstructing unevenly. The green is a normal obstruction of the half pavilion mains (lower girdle facet) it's just reflecting back the camera. Blue is the mush zone I described.
Amen
 

flyingpig

Ideal_Rock
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The bottom one sold but you can still see the video. I know it’s a lab but I’m posting it because I couldn’t find any 34/41’s in the natural section and that angle combination seems to be one where it’s hit or miss because of rounding
Both should have no significant leakage IRL. When you slight rotate videos very slightly back and forth you will see bright broad reflection going on and off for each facet under the table between the arrows.
 

cj2be

Shiny_Rock
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Both should have no significant leakage IRL. When you slight rotate videos very slightly back and forth you will see bright broad reflection going on and off for each facet under the table between the arrows.
I’m trying so hard to find a 35/40.8 as an example but can’t find one! Basically I just want to know if you can spot leakage to the naked eye when the proportions fall just beyond the ideal range or if it needs to be more dramatic than that. I know that ASET and idealscopes do the work for us but I want to train my eye! It seems like I’m confusing obstruction and leakage because I thought that those dark areas between the arrows was leakage rather than normal obstruction
 

cj2be

Shiny_Rock
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Mar 14, 2019
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GIA XXX natural 34/41 with advanced images:


GIA XXX natural 35/40.8 with advanced images:
Wow! I can see leakage for sure at 11 and maybe even 5 in that 34/41. I’m basing that off the video. Looks like the leakage is in a different position in the ASET and idealscope. Also, what are the things I circled in black?
 

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gm89uk

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These are nice ones @sledge because the Asets and photographs are not in the same orientation, so you can't cheat.
The 35/40.8 combo is more subtle but the mush is visible even in the photograph
 

flyingpig

Ideal_Rock
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That is H&A image, not idealscope.
In H&A image, contrast is white. In ASET, it is blue or black. In ideal scope, it is black.
That is contrast you circled. In fact, black (background color) is leakage in this case.
 

Karl_K

Ideal_Rock
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In slightly steep deep diamonds with some under table leakage and no to light twist it is hard to see in typical vendor videos because of the light colored background.
ASET/IS is needed to truly access them remotely.
False positive and negative is possible with just a video.
 

cj2be

Shiny_Rock
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Mar 14, 2019
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In slightly steep deep diamonds with some under table leakage and no to light twist it is hard to see in typical vendor videos because of the light colored background.
ASET/IS is needed to truly access them remotely.
False positive and negative is possible with just a video.
What do you mean by twist? Like the pavilion angle is literally twisted?
 

Karl_K

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What do you mean by twist? Like the pavilion angle is literally twisted?
The lowers between the mains(arrows) are twisted in 3d space and sometimes not flat.
This is done when there is something off in the mains so they force the lowers doing stuff the labs dont grade to get it lined up for an EX symmetry grade.
Often what they are hiding is a wide ranging pavilion angles but not always.
There have been examples that looking at scans there does not seem to be an obvious reason they did it but some of the reason are beyond the resolution of the scanners.
Or if they pick it up its not part of what is being graded so they average it away.
 

daisygrl

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I’m trying so hard to find a 35/40.8 as an example but can’t find one! Basically I just want to know if you can spot leakage to the naked eye when the proportions fall just beyond the ideal range or if it needs to be more dramatic than that. I know that ASET and idealscopes do the work for us but I want to train my eye! It seems like I’m confusing obstruction and leakage because I thought that those dark areas between the arrows was leakage rather than normal obstruction
Here is one 35/40.8 (sold out but you still can see the video). It does not have the GIA attached but it is for sure 35/40.8. Where can you see leakage with a naked eye on this one?
 

cj2be

Shiny_Rock
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Mar 14, 2019
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Here is one 35/40.8 (sold out but you still can see the video). It does not have the GIA attached but it is for sure 35/40.8. Where can you see leakage with a naked eye on this one?
To the left and right of 6 o’clock?? Lol this is fun
 
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flyingpig

Ideal_Rock
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To the left and right of 6 o’clock?? Lol this is fun
Those are the reflection of brown in the room, not leakage. Leakage in JA video would appear watery and mushy.

I will be surprised to see any blatant leakage. As noted earlier, you want to assess areas between arrow shafts and look for any oddity.
In this case, there is none and all arrows go dark. The pavilion is evenly cut and nothing above 41.
It is a very well cut 35/40.8
 

cj2be

Shiny_Rock
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Mar 14, 2019
Messages
148
Those are the reflection of brown in the room, not leakage. Leakage in JA video would appear watery and mushy.

I will be surprised to see any blatant leakage. As noted earlier, you want to assess areas between arrow shafts and look for any oddity.
In this case, there is none and all arrows go dark. The pavilion is evenly cut and nothing above 41.
It is a very well cut 35/40.8
If the arrows aren’t all dark does that mean leakage? Also, in the BE 34/41 stone from above there is 1 PA that is 41.2. Does that mark always mean there is leakage or is it when the diamond goes beyond 41.2?
 

Karl_K

Ideal_Rock
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If the arrows aren’t all dark does that mean leakage? Also, in the BE 34/41 stone from above there is 1 PA that is 41.2. Does that mark always mean there is leakage or is it when the diamond goes beyond 41.2?
The mains themselves do not leak at any sane pavilion angle it will always be the lowers between the mains.(there may be exceptions if everything were totally whacked beyond belief)

However the mains will stop responding to normal obstruction when deep.
 
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