ASET & color

[AV_]

I am taking aside here a question that came up on another thread (this):

@Rockdiamond One day I might ask you how radiants can be made to NOT show twice as much colour as there is in the rough!

it's a very intersting question- and totally affects how we interpret ASET ......sounds like fertile ground for a thread, if you wanted to start one

I could put the same question for any diamond cut, which might b easier or harder to answer!

@Rockdiamond I must admit. I have never dared read an ASET - for aparent color (in other words: for the effect of cut on color face up). I might speculate, but, I am more interested in the Dark than anything.

 

[John P]

Cool question.

My 2 cents - ASET gives the following information.

1. Does light entering the diamond in the face-up position exit through the bottom of the diamond? Areas where that happens will function like windows and appear black (if the stage under the diamond is black) or they will appear white (in rare but stricter cases where a light source is placed underneath the diamond).

2. When light enters the diamond in the face-up position and reflects back to the viewer (potentially as brightness) where in the hemisphere is that light coming from? Light drawn from 90° directly above down to 75° will appear blue. Light drawn from 75° down to 45° above will appear red. Light drawn from 45° down to the horizon will appear green.

That's all.

There is no information about intensity, ray-paths or apparent color raising or lowering due to light return intensity or (alternately) inefficiency.

It is certainly possible to draw conclusions about potential brightness vs darkness in certain lighting conditions based on ratio and distribution of the colors. Experienced users can also draw reliable conclusions about contrast. The more diamonds one has viewed in ASET, across a broad range of classes and categories, the more useful the information becomes - but face-up color improvement or dis-improvement is not on the menu in my experience. Hope that helps.

 

[AV_]

@John Pollard High contrast does seem to play with color perception - mostly against, some black among white flash drowns everything.

I expect to see colour from white or green ASET areas, but do not count on it - I cannot guess the type of light path, even in a familiar cut [rookie].

 

[John P]

To make sure we're on the same page: We are discussing 'colour' as chemical, not dispersive, correct? So seeing 'colour' here (common example) implies yellow or brown tint in the body of the diamond, yes?

I expect to see colour from white or green ASET areas, but do not count on it - I cannot guess the type of light path, even in a familiar cut [rookie].

Presuming we are on the same page, above: Would you expect to see colour in those areas if the subject is a Type IIa colorless diamond?

PS: You're not such a rookie.

 

[AV_]

I was thinking of perceived colour - in an impressionistic sense, so the contrast pattern can be said to matter aside the relevant absorption spectrum of the rough & the optics of the cut.


Digressing... funny you should mention a leaky colourless IIa - the first serious diamond that got me interested, some years before PS, was a thumb sized perfect tablet made for some laboratory use. I still have not seen anything as transparent! [likely because of the polish, but... of course it is also a very, very transparent thing.]

 

[Karl_K]

Depends on the lighting environment and viewing angle if color is seen.
Now if your talking about body color the above applies plus few people can even in optimal conditios see color differences in the colorless range face up..

 

[diagem]

I was thinking of perceived colour - in an impressionistic sense, so the contrast pattern can be said to matter aside the relevant absorption spectrum of the rough & the optics of the cut.


Digressing... funny you should mention a leaky colourless IIa - the first serious diamond that got me interested, some years before PS, was a thumb sized perfect tablet made for some laboratory use. I still have not seen anything as transparent! [likely because of the polish, but... of course it is also a very, very transparent thing.]

Hope I am understanding you, but you can (with ample experience) pick up certain obstructions (not necessarily contrast) and translate them into color retention zone reflections such as girdle reflections etc... which cause color to appear optically.

 

[AV_]

Hope I am understanding you...

Perfectly, of course!

 

[AV_]

Now is my turn to not quite understand - what do you mean by:

certain obstructions (not necessarily contrast)

?

 

[diagem]

Now is my turn to not quite understand - what do you mean by:

Diagem said:

certain obstructions (not necessarily contrast)

?

Well, generally speaking, most fancy colored diamonds are currently cut to exhibit color retention zones.
Both intense light return (e.g. red in ASET) or physical external obstructions (e.g. blue in ASET) which are reflected by objects from the environmental space are considered optical negatives, at least in the current world of colored diamonds where face-up color appearance rules.

This is relating more to what John Pollard mentioned above as “dispersive color vs. physical material color”. Or as you mentioned yourself as impressionistic color.

I myself consider purposely designed internal girdle reflections etc.. as types of obstructions to pure light return.

That is why I asked that I hope I am understanding your question.

 

[Karl_K]

While how to do it is complicated the broad concept is easy.
Tuning for Light return - Short light paths - get the light out as quick and as efficiently as possible.
Tuning for face up color - Long light paths and reflections from inside the stone. The light is in the diamond longer and travels through more material.

 

[Karl_K]

Pears are interesting as a lot of pears have areas of short lights paths and areas of very long light paths.
Its pretty clear which is which here in this model.

 

[John P]

Pears are interesting as a lot of pears have areas of short lights paths and areas of very long light paths. Its pretty clear which is which here in this model.

Nice example. Can you post the CGI ASET?

 

[diagem]

Nice example. Can you post the CGI ASET?

I am sure you can translate into ASET colors for us...
Merry Christmas Sir...

 

[Karl_K]

Nice example. Can you post the CGI ASET?

Its the stock pear in DC 3.x if you want to play with it further.
Here is the ASET white both colorless and yellow "diamond".

 

[John P]

Merry Christmas Sir...

Merry and Happy to you and yours too, my friend. And to all.

 

[John P]

Thanks Karl.

Putting them all together.

My 2 cents - ASET gives the following information.

1. Does light entering the diamond in the face-up position exit through the bottom of the diamond? Areas where that happens will function like windows and appear black (if the stage under the diamond is black) or they will appear white (in rare but stricter cases where a light source is placed underneath the diamond).

2. When light enters the diamond in the face-up position and reflects back to the viewer (potentially as brightness) where in the hemisphere is that light coming from? Light drawn from 90° directly above down to 75° will appear blue. Light drawn from 75° down to 45° above will appear red. Light drawn from 45° down to the horizon will appear green.

That's all.

There is no information about intensity, ray-paths or apparent color raising or lowering due to light return intensity or (alternately) inefficiency.

It is certainly possible to draw conclusions about potential brightness vs darkness in certain lighting conditions based on ratio and distribution of the colors. Experienced users can also draw reliable conclusions about contrast.

The more diamonds one has viewed in ASET, across a broad range of classes and categories, the more useful the information becomes - but face-up color improvement or dis-improvement is not on the menu in my experience.

I'll admit to thinking normal range, not FCD. With the example above in-play, does anyone want to try and poke holes in my highlighted comments?

Beware, I might poke back.

 

[Karl_K]

Imho and I'm not a super expert on colored diamonds and ASET but from playing around with them in DC and talking to people.
To change the apparant face up color and eveness of a colored diamond takes a scapel view and the ASET is chainsaw view.
The ASET image tends to blend many smaller virtual facets into a blue red or green blob. If you want to change that area you need to know what interaction of the physical facets it represents and you can not do that when the virtual facets are blended together.

 

[diagem]

The darker yellow areas in the face up display less red and blue as where the lighter yellow hue is based on more red and blue??

 

[John P]

The darker yellow areas in the face up display less red and blue as where the lighter yellow hue is based on more red and blue??

Be careful with that chainsaw, sir.

 

[Garry H (Cut Nut)]

The smaller virtual facets the more colour shows.
The more green and less red the better for creating fancy colored diamonds.. Blue portions are usually totally colorless

 

[OoohShiny]

This thread makes my head hurt.



I like it lol

Imho and I'm not a super expert on colored diamonds and ASET but from playing around with them in DC and talking to people.
To change the apparant face up color and eveness of a colored diamond takes a scapel view and the ASET is chainsaw view.
The ASET image tends to blend many smaller virtual facets into a blue red or green blob. If you want to change that area you need to know what interaction of the physical facets it represents and you can not do that when the virtual facets are blended together.

Are you saying that a physical facet can be reflecting back to the viewer (in one given light path) a combination of light paths from a number of virtual facets that have coincided on a single (physical) facet?

Meaning some of the light being returned would be red and some would be green (in ASET)?

If so, would the ASET colour on that facet be red or green?


Or am I barking up the wrong tree completely, because an escaping light path from a physical facet would only be from one single virtual facet?

 

[Karl_K]

Are you saying that a physical facet can be reflecting back to the viewer (in one given light path) a combination of light paths from a number of virtual facets that have coincided on a single (physical) facet?

Sure a virtual facet can have multiple light paths of various sizes and directions that all bounce off one physical facet.

But what Im talking about is ASET blends virtual facets together and displays them as a blob rather than separate.

 

[Karl_K]

Examples of short and long light paths in the pear above.
Combine thousands and even millions and you have the light output of a diamond.

 

[OoohShiny]

,

Sure a virtual facet can have multiple light paths of various sizes and directions that all bounce off one physical facet.

But what Im talking about is ASET blends virtual facets together and displays them as a blob rather than separate.

Ahhhhh, so it's more an issue of 'resolution' than actual lightpath tracking limitations?

Have you reported the issue to see if it could be improved in an update?

 

[Karl_K]

,

Ahhhhh, so it's more an issue of 'resolution' than actual lightpath tracking limitations?

Have you reported the issue to see if it could be improved in an update?

Yea its a resolution issue, but I would consider the broad zones used(4 zones) a lightpath tracking limitation.

Its the nature of the beast and nothing that can be improvedd without throwning ASET theory out the window and replacing it.

 

[AV_]

I do not know how light path length is constructed, so relating facet size & position to reflection intensity makes sense [there is an argument here, that we likely all know & never wrote!] - as you put it, @Garry H (Cut Nut)

-

Just seen this: www - if the cut diamond matches the rough one for color, it is not easy to tell this way - the cushion shows both deeper & lighter yellows - perhaps no surprise, but quite a bit of pleasure to see it play...