Discussion of aset in simple terms

[ChunkyCushionLover]

But looking at this aset- and the actual diamond, I'm having trouble finding a correlation. For example, there's areas of green and red that have almost zig zag pattern on the aset.
In real life those are small virtual facets- but the adjacent areas are far closer in color.
Maybe the micro facet lighting up ( red on the aset) is superbright- but the micro facet reflection next to it ( green on the aset) is a very close gradient of silver. Not a lot of contrast- almost impossible to see- and contributes to the crushed ice effect

From my perspective, the fact that the simulation match the photo I took is not the issue.
I have the stone, and the aset- I don't see how we can correlate adacent areas that show stark contrast on the aset, but very slight contrast in the diamond in real life

RD,

Please rewatch the two videos I posted above. They second one was put up for your benefit.

In the first video do you see the correlation betwen the ASET and how the diamond looks under lightbox lighting?

In the second video do you see what happens when you effectively block the overhead spot lighting, now look at the two diamonds such as in Garry's store?

Conceptually you must get away from thinking ASET represents one lighting environment and the hard contrast(red/green barrier) you see in the image represents hard contrast you will see in your lighting environment it does not.

Red areas are often more intense areas (bright white), and adjacent green areas can be more of a silvery or greyish less intense white.
Look in the videos under two lighting schemes and tell me if what you are describing is being shown.

 

[Rockdiamond]

ccl- I don't find the videos you posted to be at all true to life.
That is- looking at the actual diamond, in varying lighting conditions, it does NOT have the dark areas portrayed in the vimeos you posted.

I would again ask that we use clinical terms- calling the one on the right "bright" versus the Original Radiant seems pejorative- maybe I'm overly sensitive- but I find this ORC to be remarkably bright IRL.

 

[ChunkyCushionLover]

Last one even closer.

Open simulation Parameters, unclick fast and on the right drop down select highest. Then open the Custom cut and I raised from 5 to 10. It will take a long time to render - maybe 5 times a well cut round because of the longer rays.
But you could make a much more realistic movie (over night CCL).

Well I can render 10 interactions at the highest resolution 500 frames for RD radiant took about an hour and a half at 640X480.

However I'm not sure if the resolution is too good, for other diamonds increasing interactions above 10 gives VFs your eye can't really see perhaps they are there and you just can't resolve them at such a small size, but maybe 10 is an upper practical limit?

 

[Rockdiamond]

Is it possible these aspects are causing the differences between the simulations and real life that I'm seeing?

 

[ChunkyCushionLover]

Is it possible these aspects are causing the differences between the simulations and real life that I'm seeing?

No, it will make the virtual facets smaller(more fine crushed ice) in the diamond if it has longer than 5 bounce rays and increase the resolution. This is the difference.



I don't know what you think is different between the simulated videos and what you see, because you haven't indicated or commented on the videos seen yet.

 

[ChunkyCushionLover]

At moderate magnification.

 

[Rockdiamond]

Is there any way to know how many times the light bounces in actuality, as opposed to a simulation?

The stone looks more like the "high" image, or the 10ray image- however both show much larger dark and darker dark zones than I see in real life

 

[ChunkyCushionLover]

Is there any way to know how many times the light bounces in actuality, as opposed to a simulation?

The stone looks more like the "high" image, or the 10ray image- however both show much larger dark and darker dark zones than I see in real life

RD,

What about the grey background one from Garry's store?

 

[Rockdiamond]

Sorry ccl- it's been a long day- can you post a link to the image you're referring to in Garry's store?

Again, thanks for taking the time to work on this

 

[ChunkyCushionLover]

http://www.vimeo.com/15653513

 

[Rockdiamond]

Both stones look dark with the grey background.
Can we also agree that attributing motivation behind the cut is not accurate ccl?
IOW- you categorize the stone you like better as being "cut for brightness"- the implication is somehow the other stone was not.
Knowing the person who cut the stone on the left, I can say with no doubt that that is an inaccurate characterization.
Or I'm reading too much into the labels- which is also possible.
I'm a sensitive guy

 

[ChunkyCushionLover]

Both stones look dark with the grey background.
Can we also agree that attributing motivation behind the cut is not accurate ccl?
IOW- you categorize the stone you like better as being "cut for brightness"- the implication is somehow the other stone was not.
Knowing the person who cut the stone on the left, I can say with no doubt that that is an inaccurate characterization.
Or I'm reading too much into the labels- which is also possible.
I'm a sensitive guy

RD,

We agree on:

1) The simulated and photographed ASET match, so you will no longer claim simulated images are invalid.
2) You now understand when I talk about brightness in the context of the ASET image I am referring to the percentage area of the crown which can direct light to an observer's eyes.

I'll leave it at that, I have no more time or interest in trying to help you further.

These may help you if you read them repeatedly every time you look at an ASET image.

http://www.americangemsociety.org/uploads/ASETTheory-709.pdf
http://www.ideal-scope.com/1.using_reference_chart_ASET.asp

 

[Rockdiamond]

Although the sim aset does match the real one- the sim diamonds do not. We can see this in the simple fact that by changing a few settings, we get a significantly different effect under the table. For sure the 10 bounce is closer to reality- maybe that's part of the problem.
It's possible that the light bounces more than the simulation anticipates.

I'd propose that this aset be used as a model for what Garry calls "good" crushed ice.
I really like the light performance on this one.

The difficulty is in interpretation of the aset.
As I mentioned, it's quite easy to see how a step cut's look in real life relates to it's aset.
But this is not the case here.
To say nothing of stones that exhibit a combination of tiny virtual facets with larger ones.

 

[Garry H (Cut Nut)]

Although the sim aset does match the real one- the sim diamonds do not. We can see this in the simple fact that by changing a few settings, we get a significantly different effect under the table. For sure the 10 bounce is closer to reality- maybe that's part of the problem.
It's possible that the light bounces more than the simulation anticipates.

I'd propose that this aset be used as a model for what Garry calls "good" crushed ice.
I really like the light performance on this one.

The difficulty is in interpretation of the aset.
As I mentioned, it's quite easy to see how a step cut's look in real life relates to it's aset.
But this is not the case here.
To say nothing of stones that exhibit a combination of tiny virtual facets with larger ones.

The number of bounces is much more an issue for modelling crushed ice than it is for a well cut round (that has much less impact from multiple bounces).

David I do not think this is an exepmlar for crushed ice because there are very bright parts on either side and the overall center of the stone shows a pattern - like an oval or rounded effect inside the table.
The bright parts show up as red and blue in AEST and they are from high angled light sources and have large virtual facet areas.

 

[Rockdiamond]

The number of bounces is much more an issue for modelling crushed ice than it is for a well cut round (that has much less impact from multiple bounces).

David I do not think this is an exepmlar for crushed ice because there are very bright parts on either side and the overall center of the stone shows a pattern - like an oval or rounded effect inside the table.
The bright parts show up as red and blue in AEST and they are from high angled light sources and have large virtual facet areas.

As far as your first point, we're in total agreement.
It's probably easiest modeling a step cut.

IN terms of the second point- I find this stone to be an exemplary example of non patterned crushed ice. There are simply no large dark areas- no medium sized ones even. I'm looking at the stone, not the aset.
For context, can you show us an aset ( and or actual photos- Lbox preferably) that you feel to show the crushed ice look?

 

[Garry H (Cut Nut)]

David I do not think this is an exepmlar for crushed ice because there are very bright parts on either side and the overall center of the stone shows a pattern - like an oval or rounded effect inside the table.
The bright parts show up as red and blue in AEST and they are from high angled light sources and have large virtual facet areas.

IN terms of the second point- I find this stone to be an exemplary example of non patterned crushed ice. There are simply no large dark areas- no medium sized ones even. I'm looking at the stone, not the aset.
For context, can you show us an aset ( and or actual photos- Lbox preferably) that you feel to show the crushed ice look?

I will find and example. But one stone I saw a couple of years back - about a 5ct fancy yellow radiant at Dehres at the HK trade fair - was an excellent example. They allowed me to take a series of photos and the stone stayed like this one from their site up until about 15 degrees of rocking each side. The pinfire was even and there were no differences at any zone across the stone from side to side.

Post another photo of your ORC stone David and I will show you what I mean. But from memory - we can see the pink from your fingers in the photo = the stone is returning high angle light.

Also try the trick of moving in and out with ASET - that will help you get the point CCL is making - that the cut of between red and blue is very different light to the cut off between red and green. Notice some red turns green and some turns blue. And some red just stays red all the time.
But please - it is not a criticism of your stone - it is just a different look.

 

[Rockdiamond]

(jaw drops) man, what an amazing stone, based on that image- wow.
I'd love to see the aset for that one, for the purposes of this discussion.
And- the Radiant we're using here for comparison, to me, in real life- is as good as the photo of the Fancy Yellow.

Post another photo of your ORC stone David and I will show you what I mean. But from memory - we can see the pink from your fingers in the photo = the stone is returning high angle light.

Also try the trick of moving in and out with ASET - that will help you get the point CCL is making - that the cut of between red and blue is very different light to the cut off between red and green. Notice some red turns green and some turns blue. And some red just stays red all the time.
But please - it is not a criticism of your stone - it is just a different look.

No offense taken whatsoever Garry. It's actually not our stone, and I've removed it from the website so we can discuss it.
Here's a shot in the parcel paper



A shot taken a little further from the camera- messy desk in the background


A shot using bright lighting above the diamond

 

[Garry H (Cut Nut)]

(jaw drops) man, what an amazing stone, based on that image- wow.
I'd love to see the aset for that one, for the purposes of this discussion.
And- the Radiant we're using here for comparison, to me, in real life- is as good as the photo of the Fancy Yellow.

Post another photo of your ORC stone David and I will show you what I mean. But from memory - we can see the pink from your fingers in the photo = the stone is returning high angle light.

Also try the trick of moving in and out with ASET - that will help you get the point CCL is making - that the cut of between red and blue is very different light to the cut off between red and green. Notice some red turns green and some turns blue. And some red just stays red all the time.
But please - it is not a criticism of your stone - it is just a different look.

No offense taken whatsoever Garry. It's actually not our stone, and I've removed it from the website so we can discuss it.
Here's a shot in the parcel paper



A shot taken a little further from the camera- messy desk in the background


A shot using bright lighting above the diamond

Excellent series of photo's.
You can see the shot at a distance has much less of the dark zone effects.
One thing we notice in all your shots is you are often too close to the stone with the camera.
If you get someone to measure how far away you are from stones and measure the lens size and camera bory type etc I am sure we can turn it into angles and possibly help solve some problems we have here.

The red ovals show a pattern - my earlier definition rules out patterns in crushed ice. But it is just my definition - what do others think?

The blue zones are obstruction which are clearly not present in the yellow diamond from Dehre's - because we do not have a standard for your photo's - all we have is the ASET to go by - it seems that most observers would see these dark zones and therefore the stone would not be "even"

 

[Rockdiamond]

I can totally see your point about photography Garry.
It's really awesome to have this dialog in a more relaxed manner.

It has been my habit to shoot very close to the diamond. The advantages are very good views of the facet structure and imperfection, if it exists.
I've gotten some new equipment that produced these newer photos.
I believe the best possible representation is going to involve close up photos in combination with things like hand shots and distance shots to give the most complete perspective.
The Lbox is actually the best at these type of super close ups. But there are inherent disadvantages in a highly magnified photo.
The same could be said of any photo- so a variety is best IMO
The radiant is about 18 inches from my face now - sitting on the desk- and there are NO dark areas greater than 1% of the stone's size visible.

 

[Garry H (Cut Nut)]

I can totally see your point about photography Garry.
It's really awesome to have this dialog in a more relaxed manner.

It has been my habit to shoot very close to the diamond. The advantages are very good views of the facet structure and imperfection, if it exists.
I've gotten some new equipment that produced these newer photos.
I believe the best possible representation is going to involve close up photos in combination with things like hand shots and distance shots to give the most complete perspective.
The Lbox is actually the best at these type of super close ups. But there are inherent disadvantages in a highly magnified photo.
The same could be said of any photo- so a variety is best IMO
The radiant is about 18 inches from my face now - sitting on the desk- and there are NO dark areas greater than 1% of the stone's size visible.

As some have said to you - a good macro lens that takes close up - but with the lens at a distance is important.

I cant find my definition that I wrote last week - any one able to?

I need to add a viewing distance - I propose 12- 14 inches.
Buyers are almost always going to inspect from closer than 18 inches David.
AGS and the US military use 8 inches.
Any thoughts?

 

[stone-cold11]

This one unless there is a newer one? From about a month ago? 2nd post from the last.

https://www.pricescope.com/communit...ions-bad.148696/page-24#post-2710693#p2710693

 

[Rockdiamond]

IN terms of viewing distance- this is really related to all the other concerns about photography. This relates to aset as well.
Whatever we set as a "benchmark" will exclude other possibilities that will be the norm for other types of viewing.

For example- I agree, when the box comes, and people open it up to inspect, they will indeed view from less than 18inches.
However I'd say that 18inches is a lot more realistic when we consider a more general manner of looking at one's diamond.

In preparation for the (eagerly awaited) lbox, I did buy an SLR, with a macro.
I started with a 100mm lens which did force me further away from the subject.
But than it is a matter of my eyes- and being able to compose the photo with focus where I want. Getting further away hinders that.
50mm makes focusing a lot easier.
I can still get further away than before

 

[Garry H (Cut Nut)]

This one unless there is a newer one? From about a month ago? 2nd post from the last.

https://www.pricescope.com/communit...ions-bad.148696/page-24#post-2710693#p2710693

 

[Garry H (Cut Nut)]

IN terms of viewing distance- this is really related to all the other concerns about photography. This relates to aset as well.
Whatever we set as a "benchmark" will exclude other possibilities that will be the norm for other types of viewing.

For example- I agree, when the box comes, and people open it up to inspect, they will indeed view from less than 18inches.
However I'd say that 18inches is a lot more realistic when we consider a more general manner of looking at one's diamond.

In preparation for the (eagerly awaited) lbox, I did buy an SLR, with a macro.
I started with a 100mm lens which did force me further away from the subject.
But than it is a matter of my eyes- and being able to compose the photo with focus where I want. Getting further away hinders that.
50mm makes focusing a lot easier.
I can still get further away than before

I am afraid that you bought the wrong camera David.

FYI GIA claim to have used 14 to 20 inches (35-50cm) observation distances.
I believe a little closer than 18 inches is better.

I have obtained a model of a real polished model of a great crushed ice stone - will post a movie asap. But because of the huge number of reflections it has taken 45 minutes to record 100 of 300 frames and my lap top is nearly melting. It is proprietary and afraid I can not pass it on.

 

[Garry H (Cut Nut)]

Here is a video of an especially good crushed ice stone made in DiamCalc from a real stone scan.

http://www.youtube.com/watch?v=VmLjq4zXI_U

This is a movie of a real diamond modeled 3D scan in DiamCalc with 12 reflections to get realistic imagery.

Good crushed ice diamonds appear, from around 14 inches or 35cm, to have an overal even array of very small flashes that 'roll' as the stone is rocked from side to side. There should be no easily identified larger dark zones (which can be most commonly the result of larger head obstruction, or leakage caused dark zones). All the flashes should be very small resuting in a pinfire effect.
The cause of the appearance of an exceptionally large number of facets is the many internal reflections which split the observed facet structure at each internal reflection.
The contrast between bright and dark areas is often contributed to positively by very small zones of leakage, where-as in well cut rounds the main cause of (larger) contrasting dark zones is obstruction as per the way the star effect often appears dark and with a slight movement the dark quickly flashes to a very intense bright zone.
A good crushed ice diamond will apear to be less bright when compared beside a good round in most lighting scanrios, but the overall uniform brightness can make these stones appealing.

I have rarely seen good colorless crushed ice diamonds, but frequently see good examples in colored diamonds where there is a much larger premium for the skill and expertise involved in producing the color adding benefits resulting from the longer ray paths.

I propose the above to become a standard Pricescope definition for crushed ice appearance. Does anyone care to add or subtract? Should I start a new thread?

 

[ChunkyCushionLover]

Here is a video of an especially good crushed ice stone made in DiamCalc from a real stone scan.

http://www.youtube.com/watch?v=VmLjq4zXI_U

This is a movie of a real diamond modeled 3D scan in DiamCalc with 12 reflections to get realistic imagery.

Good crushed ice diamonds appear, from around 14 inches or 35cm, to have an overal even array of very small flashes that 'roll' as the stone is rocked from side to side. There should be no easily identified larger dark zones (which can be most commonly the result of larger head obstruction, or leakage caused dark zones). All the flashes should be very small resuting in a pinfire effect.
The cause of the appearance of an exceptionally large number of facets is the many internal reflections which split the observed facet structure at each internal reflection.
The contrast between bright and dark areas is often contributed to positively by very small zones of leakage, where-as in well cut rounds the main cause of (larger) contrasting dark zones is obstruction as per the way the star effect often appears dark and with a slight movement the dark quickly flashes to a very intense bright zone.
A good crushed ice diamond will apear to be less bright when compared beside a good round in most lighting scanrios, but the overall uniform brightness can make these stones appealing.

I have rarely seen good colorless crushed ice diamonds, but frequently see good examples in colored diamonds where there is a much larger premium for the skill and expertise involved in producing the color adding benefits resulting from the longer ray paths.

I propose the above to become a standard Pricescope definition for crushed ice appearance. Does anyone care to add or subtract? Should I start a new thread?

Garry,

I've already commented and modified that definition here https://www.pricescope.com/communit...set-image.150479/page-2#post-2731723#p2731723
What do you think?

That stone example does have a dark zone(leakage near the culet) and other patterned and medium sized VFs under the table with some obstruction regions. Looks like upon tilt these move so its no big deal but the distinction is worth making.
I would want to see the stone upon tilt with a .gem to see if that area changes upon slight tilt but it doesn't quite fit your definition and very few diamonds would.

Can you post the .gem file please.

 

[stone-cold11]

Garry, can you do a clip on that stone with ASET too?

 

[ChunkyCushionLover]

Also I should point out it is extremely difficult to control the uniformity of light return signature and VF patterns in rectangular stones, symmetry constraints are important. With larger LW ratios it is almost impossible to achieve anywhere close to your definition of uniformity.Modification has to be more than just tuning the facet angles it would require a facet structure redesign.

 

[Rockdiamond]

Here is a video of an especially good crushed ice stone made in DiamCalc from a real stone scan.

http://www.youtube.com/watch?v=VmLjq4zXI_U

This is a movie of a real diamond modeled 3D scan in DiamCalc with 12 reflections to get realistic imagery.

Good crushed ice diamonds appear, from around 14 inches or 35cm, to have an overal even array of very small flashes that 'roll' as the stone is rocked from side to side. There should be no easily identified larger dark zones (which can be most commonly the result of larger head obstruction, or leakage caused dark zones). All the flashes should be very small resuting in a pinfire effect.
The cause of the appearance of an exceptionally large number of facets is the many internal reflections which split the observed facet structure at each internal reflection.
The contrast between bright and dark areas is often contributed to positively by very small zones of leakage, where-as in well cut rounds the main cause of (larger) contrasting dark zones is obstruction as per the way the star effect often appears dark and with a slight movement the dark quickly flashes to a very intense bright zone.
A good crushed ice diamond will apear to be less bright when compared beside a good round in most lighting scanrios, but the overall uniform brightness can make these stones appealing.

Here's a few areas where we disagree. There are many common lighting scenarios where the crushed ice stone outshines a well cut RBC- direct sunlight, for example.
In response to your statement below: I have seen many great examples of colorless crushed ice- but like any well cut stones, they are the exception, rather than the rule.

I have rarely seen good colorless crushed ice diamonds, but frequently see good examples in colored diamonds where there is a much larger premium for the skill and expertise involved in producing the color adding benefits resulting from the longer ray paths.

I propose the above to become a standard Pricescope definition for crushed ice appearance. Does anyone care to add or subtract? Should I start a new thread?

I do love my new camera- the macro lens is simply amazing for taking photos of people- and I've gotten some very nice diamond shots with it as well.....
It seems that my 18inch idea matches with GIA's thoughts........

The movie you did is excellent Garry- it does resemble the video I took of the radiant I've been using in this discussion- although I take it through a far wider range of viewing angles.

 

[ChunkyCushionLover]

Here is a video of an especially good crushed ice stone made in DiamCalc from a real stone scan.

http://www.youtube.com/watch?v=VmLjq4zXI_U

This is a movie of a real diamond modeled 3D scan in DiamCalc with 12 reflections to get realistic imagery.

Good crushed ice diamonds appear, from around 14 inches or 35cm, to have an overal even array of very small flashes that 'roll' as the stone is rocked from side to side. There should be no easily identified larger dark zones (which can be most commonly the result of larger head obstruction, or leakage caused dark zones). All the flashes should be very small resuting in a pinfire effect.
The cause of the appearance of an exceptionally large number of facets is the many internal reflections which split the observed facet structure at each internal reflection.
The contrast between bright and dark areas is often contributed to positively by very small zones of leakage, where-as in well cut rounds the main cause of (larger) contrasting dark zones is obstruction as per the way the star effect often appears dark and with a slight movement the dark quickly flashes to a very intense bright zone.
A good crushed ice diamond will apear to be less bright when compared beside a good round in most lighting scanrios, but the overall uniform brightness can make these stones appealing.

Here's a few areas where we disagree. There are many common lighting scenarios where the crushed ice stone outshines a well cut RBC- direct sunlight, for example.
In response to your statement below: I have seen many great examples of colorless crushed ice- but like any well cut stones, they are the exception, rather than the rule.

I have rarely seen good colorless crushed ice diamonds, but frequently see good examples in colored diamonds where there is a much larger premium for the skill and expertise involved in producing the color adding benefits resulting from the longer ray paths.

I propose the above to become a standard Pricescope definition for crushed ice appearance. Does anyone care to add or subtract? Should I start a new thread?

I do love my new camera- the macro lens is simply amazing for taking photos of people- and I've gotten some very nice diamond shots with it as well.....
It seems that my 18inch idea matches with GIA's thoughts........

The movie you did is excellent Garry- it does resemble the video I took of the radiant I've been using in this discussion- although I take it through a far wider range of viewing angles.

That video you finally like????
Jewelry store lighting with white background, with 12 bounces.

Well here is the ORC radiant with the same lighting as gary used for his cushion and 12 bounces.
http://www.youtube.com/watch?v=pmCp-Xaff14&fmt=22

20 degree up down tilt.

As you can see this diamond has a lot more contrast zones than Garry's square cushion example.