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What’s Advance ASET and Dynamic Contrast?

sledge

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Awhile back @Serge posted some stones with what I recall (or at least want to reference) as "advanced ASET imaging".

As we know ASET imaging today, it is static. The image Serg provided was an ASET that moved; therefore, capturing how the stone's performance may alter as it's rotated/tilted.

When trying to find an example I saw another interesting article. This talks about how BGD Black shows two different ASET images on the AGS cert. The jist being AGS normally shows 1 image @ 33.5 degrees, whereas the BGD Black version of the AGS cert shows both a 30 and 40 degree ASET image.

Similar to what I was referring to with Octonus/Serg except the images are on an AGS cert and are still images captured at various degrees of motion. The "image" Serg provided was like an animated GIF that showed the stone in actual motion vs just captured still photos at various degrees of rotation.

 

Double E

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Awhile back @Serge posted some stones with what I recall (or at least want to reference) as "advanced ASET imaging".

As we know ASET imaging today, it is static. The image Serg provided was an ASET that moved; therefore, capturing how the stone's performance may alter as it's rotated/tilted.

When trying to find an example I saw another interesting article. This talks about how BGD Black shows two different ASET images on the AGS cert. The jist being AGS normally shows 1 image @ 33.5 degrees, whereas the BGD Black version of the AGS cert shows both a 30 and 40 degree ASET image.

Similar to what I was referring to with Octonus/Serg except the images are on an AGS cert and are still images captured at various degrees of motion. The "image" Serg provided was like an animated GIF that showed the stone in actual motion vs just captured still photos at various degrees of rotation.

Thanks Sledge. It did draw my attention when I was browsing BGDs inventory. I am interested and your info provided me some idea. I am going to learn something new (for me^^)
 

sledge

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Thanks for the additional info @John Pollard. As usual, good stuff. :geek2:

I did have a few follow up questions/comments:

1. The NiceIce link I referenced had a tone that the advanced ASET imaging was something proprietary to the BGD Black cut/brand and part of what made it special. However, the AGS report provided in the linked HPD article clearly shows dual ASET images with CBI branding, which to me, indicates this report is not proprietary to any particular vendor. Correct?

104109645001-PGRH Page 001.png

2. Looking on the AGS website, I see a plethora of report options (to the point of confusing IMO). The AGS site indicates platinum as the top tier report, but does not mention advanced ASET. Is this a special request the vendor must make? Assuming so, what is the additional cost?

3. I had noticed this next question awhile back. It seems that some AGS certified stones offer the Only My Diamond options, that allow you to see additional details like a video, girdle inscription, etc on the stone in question.

Again, the CBI stone referenced in the HPD article is one such stone that offers this additional data.

I assume this would not be vendor specific either, and just a matter of requesting the additional services and likely paying a higher price for the lab report/service being provided. Is that correct? And can you share the cost premium/difference? Is there a way to obtain this data from an older stone with a platinum report?

https://agslab.com/ym-vdgr/diamonds/104109645001/home

CaptureOnlyMyDiamond.PNG


4. In regards to Dynamic Contrast, I do not feel a direct explanation was provided. It's there if you look and read carefully but I wanted to pull more attention to it.

If I have interpreted correctly, the "phantoms" mentioned in the HPD article are essentially the same thing known as dynamic contrast.

Below are screen caps of the CBI lab report provided in the HPD article, except zoomed at 500% so hopefully things are more clear and easier to identify.

Notice the left image is what you would expect the actual ASET image to appear as. However, on the right side, you pick up the additional blue areas. If you look at the color coded map below the ASET images, you will notice there is a new category called Dynamic Contrast that is a darker blue than normal contrast.

In the second screen cap, I drew yellow arrows to more easily identify them. There are 3 main arrows they show up as. I didn't draw arrows at all them, but once you see them, you can see they repeat around the diamond.

Click the images to get the benefit of the 500% zoom.

CaptureDynamic.PNG

InkedCaptureDynamic_LI.jpg
 

Karl_K

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This is nuts.
The scan data based images are not 100% photo-realistic, some are worse than others depending on specifics of the stone and scanner.
They made it worse by quietly changing the angle of obstruction used.
So to fix that they put 2 images on a report?
One of them with a more broken obstruction model than the already badly broken obstruction model 30 degree and both based on the same flawed scan data.
Nuts I tell ya!
 
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John Pollard

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Thanks for the additional info @John Pollard. As usual, good stuff. :geek2:
You're welcome. And thank you for thanking.

I did have a few follow up questions/comments: 1. The NiceIce link I referenced had a tone that the advanced ASET imaging was something proprietary to the BGD Black cut/brand and part of what made it special. However, the AGS report provided in the linked HPD article clearly shows dual ASET images with CBI branding, which to me, indicates this report is not proprietary to any particular vendor. Correct?
I presume so. The word proprietary, for us, relates to the PGR (proprietary grading report) AGS makes available to established brands. We find this extremely beneficial to end-consumers because the brand ID (for us the red Infinity icon) becomes a visible extension of the grading report. In the unfortunate case of loss having that ID helps end-consumers secure another item from the brand as insurance replacement rather than something generic.

2. Looking on the AGS website, I see a plethora of report options (to the point of confusing IMO). The AGS site indicates platinum as the top tier report, but does not mention advanced ASET. Is this a special request the vendor must make? Assuming so, what is the additional cost?
No cost beyond other AGS Platinum DLP formats.

3. I had noticed this next question awhile back. It seems that some AGS certified stones offer the Only My Diamond options, that allow you to see additional details like a video, girdle inscription, etc on the stone in question. Again, the CBI stone referenced in the HPD article is one such stone that offers this additional data. I assume this would not be vendor specific either, and just a matter of requesting the additional services and likely paying a higher price for the lab report/service being provided. Is that correct? And can you share the cost premium/difference?
OMD is an added service. I don't have the fee schedule at hand but you may be able to find it online.

Is there a way to obtain this data from an older stone with a platinum report?
The video is made when OMD is requested so it could not be provided.

4. In regards to Dynamic Contrast, I do not feel a direct explanation was provided. It's there if you look and read carefully but I wanted to pull more attention to it. If I have interpreted correctly, the "phantoms" mentioned in the HPD article are essentially the same thing known as dynamic contrast.
We did not find that to be the case. Maybe they were portents of what's has been defined as dynamic contrast by the lab. But we were unable to correlate them to actual optics.

In the second screen cap, I drew yellow arrows to more easily identify them. There are 3 main arrows they show up as. I didn't draw arrows at all them, but once you see them, you can see they repeat around the diamond.
The areas you indicate are not obstructed at 30 Blue. They are obstructed at 40 Blue. In terms of actual viewing 30 Blue is simulating obstructed areas at one viewing distance. 40 Blue shows areas that also become obstructed when you move the object closer. Imagine moving a diamond farther and closer. Less head-shadow when far (30B). More head-shadow when close (40B). It's showing contrast pattern dynamics. Ergo, dynamic contrast.

 

John Pollard

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Something specific to Pricescope culture which relates to 40 Blue. This report will show the greater obstruction drawn by certain shallow diamonds. Specifically, ideal-makes which might become recommended for earrings or pendants. Having 30 Blue and 40 Blue will help reveal whether that's a needed stipulation.
 

Texas Leaguer

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On the one hand, the “advanced ASET” could simply be described as ‘multiple ASET’ or ‘additional ASET’. In fact the 30 and 40 degree obscuration cones in the ASET lighting structure have always been integral to the ray tracing algorithms that calculate the cut grades. The 33.5 degree cone used to generate the default light map is also logical to the grading process as the software evaluates contrast at both 30 and 40 with grading apportioned on the basis of 2 parts 30 and 1 part 40.

The ‘advanced’ aspect is the highlighting of dynamic contrast. This aspect focusses attention on light coming from between 70 and 75 degrees. This is the area just outside of the more permanent obscuration zone of 30 degrees, where small tilts or movements are causing virtual facets to blink on and off. This area therefore plays an important role in scintillation and interestingly, plays and important role in fire. Partial obscuration of the overhead light source at this boundary can cause that source to appear as more of a point source (smaller subtend) which encourages the expression of dispersive fans that can be clipped by the pupil of an observer resulting in the experience of a colored sparkle (fire).

The researchers at AGSL are very interested in dynamic contrast and it will be a concept that we will likely see featured in their future work, particularly as they continue developing their grading structures for new fancy shapes.
 
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Karl_K

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In this case they hijacked a term to cover up for a mistake they made.
Changing the angle between the report and the scopes can not be described as anything but a mistake.

Dynamic contrast has been understood to be moving contrast.
This is very evident in well cut emerald cuts as you move them and watch the play of light across the stone.
While it happens in rounds due to the 8 fold symmetry it is not as visible.
To redefine that as the difference between 2 broken contrast models in wrong.
Unless someone is wearing a big blue disk on their head, one eye closed and peeling a carrot inches from there face it is totally irrelevant to the real world.
 

John Pollard

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Unless someone is wearing a big blue disk on their head, one eye closed and peeling a carrot inches from there face it is totally irrelevant to the real world.
You misspelled "carat." Plus, we don't peel. We cut and polish. Jeez.

*For anyone doesn't think that was funny, Imma ask you to lower your PS comedy standards just a skoch. :cool2:

What's interesting - advantageous even (we will see?) - is having 40 Blue printed as a supplement. It provides a new view which comes closer to GIA's obstruction model. I don't want to derail this thread with nano-tech minutia but let's remember the basis for GIA's EX grade including such an abundance of deep combos (and penalties for shallower geometries capable of AGS ideal LP) is the higher degree of obstruction used. Or, as you put it, less inches from the face.

I know it's not necessarily useful for near-Tolk proportions. But in terms of general production, proportions-correlation and education it's a look we have not seen published before. I like it.

That said, the most important headline for retailers and end-consumers peering into ASET viewers in their stores, is the fact that 30 Blue - what's published in the lab's tutorials and what you see in their official instruments, is back on their grading reports again. Yay.

I also don't mind the term dynamic-contrast. Although I think it could also be appropriately named contrast-dynamics.

Now excuse me while I put on my blue disk headpiece and resume peeling. Err. Polishing.
 

Karl_K

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rofl Sir John,
Putting the broken obstruction and even more broken obstruction model in the fridge for a second and putting down the peeler.

Printing 2 images on the report does not solve the problem of the relative accuracy between real images and the images on the report.

A times polishing the bottom of a carrot cake would give more accurate results than the images on the report. :lol::clap::dance:
 

OoohShiny

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This thread is making me hungry :lol: lol
 

sledge

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CheeSauce

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Sorry if this was asked already but what does a 40 blue image look like with a ideal cut shallower diamond and what does it look like with a less shallow diamond? In other words, how is the new image to be interpreted?
 

Karl_K

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Sorry if this was asked already but what does a 40 blue image look like with a ideal cut shallower diamond and what does it look like with a less shallow diamond? In other words, how is the new image to be interpreted?
The differences in the 2 images will be greater with shallow stones with a larger amount of blue in the 40 degree image.
 

Double E

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I hope I am not asking a strange question. Is the irregular blues next to the arrow shafts & arrow heads caused by tilting? When a stone is tilted, is it similar to changing the degree of the obstruction zone as mentioned which causes these blues? 6ED3F33A-4E1B-4CBC-8ACF-A34036334261.png
 

John Pollard

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Note: We are moving from discussion of computer-rendered ASET imprints to the topic of actual ASET photography. Actual photos are more reliable but difficult to execute. Any off-axis between camera-lens, stage and/or girdle-plane skews reflections.

Is the irregular blues next to the arrow shafts & arrow heads caused by tilting?
Those near the arrow-shafts are a simple table-reflection dynamic. Literally, a reflection of what the pavilion "sees" above. All else being equal, table-reflection increases as table-size and/or pavilion-depth increase.

Here is a prior post on obstruction, contrast and table-reflection which may be useful.
https://www.pricescope.com/community/threads/help-to-understand-diamond.238450/#post-4299145

ps-obstruction-table-reflection-with-is.jpg


You're asking a timely question in thread about ASET, since table-reflection is what determines whether the center of the diamond is red or green. Explanation and graphic here.
https://www.pricescope.com/community/threads/aset-image-help.196719/#post-3582309

When a stone is tilted, is it similar to changing the degree of the obstruction zone as mentioned which causes these blues?
If the setup is perfectly consistent tilt will increase obstruction at one compass-point of the diamond and decrease it at the opposite compass-point.

Regarding obstruction in general (blue in ASET): Bear in mind that a given diamond may show slightly less or more obstruction from one photo setup to the next, even using a standardized reflective-cone, depending the orientation of its girdle to the hemispherical base.

Using this setup as an example. The number of cutouts is limited. If the girdle's plane winds up slightly above the bottom of the ASET cone there will be slightly more obstruction in the contrast pattern.

ps-aset-graduated-cutouts.jpg


Here's table-reflection in another make of round. With a nice graphic from Garry H.
https://www.pricescope.com/community/threads/please-help-me-understand-how-bad-my-diamonds-cut-is.122699/#post-2143182
 
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John Pollard

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While we are on this dual-topic -

In case anyone has wondered why AGS doesn't provide actual photos. There are two logical reasons.

1. The lab isn’t trying to grade optical-precision. Despite some error, their mechanical scans are reliable enough to repeatably sort diamonds into overall performance grades; AGS0, AGS1, AGS2, etc. That’s the endgame, and they achieve it.

2. Taking structured-lighting-environment photos on-axis is time and labor intensive, adding cost. Additionally, most diamond producers are unconcerned with optical-precision and supply showroom jewelers (not online sellers) so a technical photo isn't interesting to them.

With that said, AGS is aware that consumer demand for video and photos on their handheld devices is increasing. We're looking forward to future developments.
 

Garry H (Cut Nut)

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AGS 40 is quite silly. It assumes a person has one eye in the midddle of their head and can focus from about 6 inches or 15cm and actually looks at diamonds from that distance.
In fact because we have 2 eyes less than 20 degree obstruction makes way more sense.
The actual images AGS print on reports is purely so they can double up and show Hearts images,
 

John Pollard

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The actual images AGS print on reports is purely so they can double up and show Hearts images
They don't print actual images Garry - unless you meant diamond-specific CGI. And the pavilion-rendering (aka hearts) appears on the DLP report format, which isn't being discussed in this thread.
 

Texas Leaguer

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AGS 40 is quite silly. It assumes a person has one eye in the midddle of their head and can focus from about 6 inches or 15cm and actually looks at diamonds from that distance.
In fact because we have 2 eyes less than 20 degree obstruction makes way more sense.
The actual images AGS print on reports is purely so they can double up and show Hearts images,
The impact of binocular vision is clearly an important topic, but the fact that AGS cut grading factors in 40 degrees of obscuration is not 'silly'. Just as the ray tracing algorithm factors in various degrees of tilt, analyzing how contrast increases at very close examination is important as well.

For more on the underpinnings of the AGS light performance cut grading system:

Section 5.3
When a gemstone is in movement the contrast pattern changes in form. This effect is called dynamic contrast and adds substantial appeal to the appearance of a stone as statically shown in Fig. 11 with a series of tilt maps ranging from −30 to 30 deg in 5-deg intervals. Contrast, as represented by the blue region in the ASET maps, is acquired by blocking a cone of 30 deg in the angular spectrum. Additional information about contrast is obtained by increasing the angular spectrum obscuration to 40 deg. This increased obscuration represents having the observer looking closer at the stone, closer than 250 mm, and it is used to critically evaluate the contrast properties of gemstones in the face-up position. Figure 12 shows the ASET maps for the Tolkowsky cut with 30 and 40 deg of obscuration. The fact that the Tolkowsky cut retains a wellbalanced contrast pattern in these two views indicates superiority in creating structured lighting. Thus characterizing gem contrast is essential in assessing the visual appeal of gemstones.
 

flyingpig

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Question for all.
A typical handheld ASET consist of green (0-45 deg), red (45-75 deg), and blue (75-90 deg).
When you say "AGS 40", "ASET 40" or "40 deg of obstruction, does it mean blue is 50-90 deg? and red is only 45-50 deg? That's an extremely narrow range for red.
 

John Pollard

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Question for all.
A typical handheld ASET consist of green (0-45 deg), red (45-75 deg), and blue (75-90 deg).
When you say "AGS 40", "ASET 40" or "40 deg of obstruction, does it mean blue is 50-90 deg? and red is only 45-50 deg? That's an extremely narrow range for red.
Since 90 degrees is perpendicular to the center of the hemisphere, 30 degrees of obstruction really means descending 15 degrees from 90.

So, 75-90 is 30 degrees of total obstruction. 70-90 is 40 degrees.
 
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