ASET considerations for stones hung as pendants?

[Venzen007]

For those with a clear understanding of what's going on in an ASET image (I don't quite count myself as one of you), given the typical position and orientation of a pendant diamond, should I be considering looking at potential pendant diamonds oriented a different way under the ASET instead of face up?

 

[OoohShiny]

For those with a clear understanding of what's going on in an ASET image (I don't quite count myself as one of you), given the typical position and orientation of a pendant diamond, should I be considering looking at potential pendant diamonds oriented a different way under the ASET instead of face up?

I thought most pendants faced out from the chest - so the viewer would be facing the top of the stone, as one would be when looking at a ring.

The ASETscope images should therefore be approached in exactly the same manner, IMO.

 

[Karl_K]

Actually ASET theory falls flat on its face in a pendant.
Obstruction is much much smaller because the social viewing distance is much longer, and if high angle ceiling/sky light in the brightest with the table up then with the table pointed to the side then the brightest light is low angle relative to the diamond table.
So all the assumptions used in ASET are false in a pendant.
You also have much larger area of contrast directly behind the diamond which also changes things.

That said many designs are not totally directional so they work but you could design a diamond in ASET that looks awful in a pendant and not break ASET theory face towards the ceiling.

 

[Venzen007]

Actually ASET theory falls flat on its face in a pendant.

From my developing understanding, that's what I was thinking. So, knowing it's going to be a pendant, is there a different way I can use the ASET, different things to look for, etc.?

Would I want to see more green, then, in a face up ASET? Or just a very even mix of green and red, not heavy on either?

 

[Karl_K]

From my developing understanding, that's what I was thinking. So, knowing it's going to be a pendant, is there a different way I can use the ASET, different things to look for, etc.?

Would I want to see more green, then, in a face up ASET? Or just a very even mix of green and red, not heavy on either?

What shape?

 

[Venzen007]

Asscher, hung like a kite rather than a box.

 

[Karl_K]

Asscher, hung like a kite rather than a box.

Awesome I have mine mounted that way.
But it brings up a conflict of interest for me because I designed a version of the asscher cut that is on the market so there is a conflict of interest.

I can say that due to the 3 or more pavilion rows pointing in different directions asschers do very well in pendants.
Instead of like an RB all the pavilion facets pointing in the same general direction, think a cone shape an asscher has 3 rows of pavilion facets pointing in 3 different directions.
https://www.pricescope.com/articles/virtual-facets-and-patterns-discussion-about-step-cuts
This can be enhanced with a smaller table and high crown.
What makes it tricky is that it can look red in ASET in an area but have a very strong light path in the green zone also.
So more green is not always better.
I need to think on this how to explain it within the rules and make it easy enough to be useful.

 

[AV_]

Would wish for substantially more blue/black on the ASET.

 

[Venzen007]

I think I saw that somewhere, that a red area in an ASET, could be returning both red angle light and green angle where, if you could somehow block the light coming from the red direction, the same area would then show green? Is that right?

But yes, if you can think of a way to explain what I need to look for, knowing it's going the pendant route, I'm all eyes.

If it helps the conflict, I'll say that I've already got a group of standard-ish asschers from which I'm choosing for this peice, but I'm interested in learning about the asscher you designed from an academic standpoint.

 

[Venzen007]

Would wish for substantially more blue/black on the ASET.

I want to be sure I understand. Blue are the areas that would return light coming in pretty perpendicular to the table, but because your eye or camera is perpendicular to the table, those areas don't get light to reflect because of those obstructions?

Wouldn't those areas stay obstructions anytime someone is looking straight at the face, regardless of where the light is coming from?

 

[Karl_K]

I think I saw that somewhere, that a red area in an ASET, could be returning both red angle light and green angle where, if you could somehow block the light coming from the red direction, the same area would then show green? Is that right?

Yes

 

[Karl_K]

Wouldn't those areas stay obstructions anytime someone is looking straight at the face, regardless of where the light is coming from?

Distance is the difference, ASET assumes a viewing distance of 25cm where the blue disk(representing a person lol) is blocking a large amount of the area the diamond is drawing light from.
Anyone that close is not likely interested in what the pendant is looking like.

 

[Karl_K]

blue is even higher angle than red so if the blue has a secondary green light path its ok.
But in a pendant its still looking for light in the wrong area even if the obstruction is much less.

 

[Karl_K]

ASET sideways

Aset

 

[Venzen007]

Got it, so when the viewer is farther away, those blue areas in the ASET image get the opportunity to reflect the light coming in perpendicular--ish to the table?

 

[Karl_K]

Got it, so when the viewer is farther away, those blue areas in the ASET image get the opportunity to reflect the light coming in perpendicular--ish to the table?

Yes but they may or may not have other strong lightpaths(red/green) also.

 

[Venzen007]

So, all this said, is an ASET tool helpful for sorting between a handful of potential asschers destined for a pendant?

Though I feel I'm learning more about the ASET tool and it's images, I'm still hazy on whether I can use it in some adjusted/interpretative way too assess pendant performance or is that simply an overextension of the ASET's capabilities? If it is, do I have another objective way to compare them or am I left with just my novice, unaided eyeballs?

 

[AV_]

They look like shards of mirror (appearing & disappearing from/to nothing!), unless precisely shaded. I tend to like this trick diamonds do too much.

...to put this in terms of raytracing, I'd need to rely on a fairly contrived light environment - or think of too many thereof...

 

[Karl_K]

So, all this said, is an ASET tool helpful for sorting between a handful of potential asschers destined for a pendant?

Between a handful of relatively well cut ones, not so much, to eliminate a lot of sucky ones. yea.

 

[Garry H (Cut Nut)]

Sorry I am late to the party.
It is more.important to gather light from the blue and blue red border than th green in my view.
Light from green in the upper hemisphere in most cuts will.result in a half bright half dark big zones.

That is why I have always told people and HCA like shallow round cut diamonds for earrings and pendants. I have done many simple training tests with my staff. They all get it. It amazes me people do not do these simple tests . And we sperate shallow stones for body wear.

In addition to the larger spread shallow diamonds do not show dirt as much. Jewelrs will tell you people see their rings and know how dirty they are but earrings rarely get cleaned.
So asscher is a bad choice. Unless you can get a shallow one. The leakage is a killer in deeper stones when dirty. A carre is bad too because half will likely go black.

 

[Garry H (Cut Nut)]

Also.
Brightness and brilliance win over pattern and fire.

 

[Gnmu]

Yes

I just got a major case of deja vu.

 

[Venzen007]

I just got a major case of deja vu.

Yep. Your ASET Scope theory post was the catalyst for my question regarding whether a traditionally ideal ASET was predictive of diamond-as-a-pendant performance.

 

[Karl_K]

Sorry I am late to the party.
It is more.important to gather light from the blue and blue red border than th green in my view.
Light from green in the upper hemisphere in most cuts will.result in a half bright half dark big zones.

That is why I have always told people and HCA like shallow round cut diamonds for earrings and pendants. I have done many simple training tests with my staff. They all get it. It amazes me people do not do these simple tests . And we sperate shallow stones for body wear.

In addition to the larger spread shallow diamonds do not show dirt as much. Jewelrs will tell you people see their rings and know how dirty they are but earrings rarely get cleaned.
So asscher is a bad choice. Unless you can get a shallow one. The leakage is a killer in deeper stones when dirty. A carre is bad too because half will likely go black.

While I agree that a high crown small table with a pavilion on the shallow side and longer lowers is as good as a modern RB is going to get in a pedant a well cut asscher has a much stronger off axis light draw due the pavilion reflectors being a diverging angles.
A MRB is to directional to be the uiltimate pendant stone.
As far as depth goes it is where the depth is that matters in asschers if its all in the pavilion then I agree its not that great but if its in the crown that is a whole nuther ball game.
The best is probably a high dome tip up pear cut.

 

[Gnmu]

Sorry I am late to the party.
It is more.important to gather light from the blue and blue red border than th green in my view.
Light from green in the upper hemisphere in most cuts will.result in a half bright half dark big zones.

@Garry H (Cut Nut) Could you elaborate on what this means? Are you saying that if I tilt the diamond away from the upper hemisphere such that light is entering from above in the green zone angle (0-45 relative to table plane) with little light coming from the blue/blue-red zone angles, most cuts will show large regions of dark/brightness?

 

[Karl_K]

@Garry H (Cut Nut) Could you elaborate on what this means? Are you saying that if I tilt the diamond away from the upper hemisphere such that light is entering from above in the green zone angle (0-45 relative to table plane) with little light coming from the blue/blue-red zone angles, most cuts will show large regions of dark/brightness?

Yes many will and those designed for just red zone light return to be be the ultimate in ASET can be worse than other designs/proportions.

 

[Karl_K]

Also.
Brightness and brilliance win over pattern and fire.

I get what your saying but it is not that simple.
For a diamond to return light it has to be able to draw light from where there is light is the bottom line.
Because of the greater distance patterns do tend to fade.
But a large flash of fire is more visible across the room than a small bright dot.

 

[Venzen007]

@Karl_K (or anyone else reading with experience setting asschers as pendants), do you have any suggestions for setting-design for kite-hung asschers to best accomodate the nature of the cut? Any setting designs/characteristics to avoid that would diminish the shape's ability to receive and return light?

 

[Karl_K]

@Karl_K (or anyone else reading with experience setting asschers as pendants), do you have any suggestions for setting-design for kite-hung asschers to best accomodate the nature of the cut? Any setting designs/characteristics to avoid that would diminish the shape's ability to receive and return light?

per the forum rules I can not post a picture of mine but it is on the board.
I like simple settings,.
Mine is set with the prongs on the sides not the corners and I like it that way for a kite set pendant.

 

[Venzen007]

Can you email me a link or photo?

Outside of that, nothing comes to mind as setting structures to avoid or can you recommend someone here to address it?