Tom and Miriam Tashey, Nancy Stacy, Thom Underwood, et al - videos

[adamasgem]

Date: 12/20/2006 2:09:28 AM
Author: Garry H (Cut Nut)
Not sure if i can really dig you guys

One of you has a sick sense of humour, and the other is spraying butt's with oil ????????????????

Boy Garry, you can't take a joke.. Anyway, this should save you the time to try to prove a proven point.

This is the effect (in 2D) of a layer of grease (RI~1.5) on the pavillion, similar to a layer of cooking oil on the pavilion..

1000 input rays distributed uniformly +/- 25 degrees from table normal (high angle lighting)
Dark Green is reflected ray
Light Green is refracted ray from internal to the diamond
RED is refracted light loss through the pavailion

Grease, cooking oil, body oil, all have about the same RI.
The red is the pavilion light loss..The increased light loss out of the pavilion is why diamonds get dull when they accumulate gunk on the pavilion of the stone.

CLEAN YOUR DIAMONDS.. NEED I SAY MORE..

 

[Garry H (Cut Nut)]

Date: 12/20/2006 3:38:37 AM
Author: adamasgem

Date: 12/20/2006 2:09:28 AM
Author: Garry H (Cut Nut)
Not sure if i can really dig you guys

One of you has a sick sense of humour, and the other is spraying butt''s with oil ????????????????

Boy Garry, you can''t take a joke.. Anyway, this should save you the time to try to prove a proven point.

Sorry Marty, butt you missed the point

Date: 12/20/2006 3:38:37 AM
Author: adamasgem
Dark Green is reflected ray
Light Green is refracted ray from internal to the diamond
RED is refracted light loss through the pavailion

Grease, cooking oil, body oil, all have about the same RI.
The red is the pavilion light loss..The increased light loss out of the pavilion is why diamonds get dull when they accumulate gunk on the pavilion of the stone.

CLEAN YOUR DIAMONDS.. NEED I SAY MORE..

Yes - you could do more - a lot more.

Use your program to predict the best performing proportion sets for diamonds with greasy pavilions please.

For example you could try comparing a straight Tolkowsky with 40.25 pavilion and 41.25 degree pavilion with the same table and crown angle.

 

[adamasgem]

Date: 12/20/2006 5:53:59 AM
Author: Garry H (Cut Nut)

Date: 12/20/2006 3:38:37 AM
Author: adamasgem

Date: 12/20/2006 2:09:28 AM
Author: Garry H (Cut Nut)
Not sure if i can really dig you guys

One of you has a sick sense of humour, and the other is spraying butt''s with oil ????????????????

Boy Garry, you can''t take a joke.. Anyway, this should save you the time to try to prove a proven point.

Sorry Marty, butt you missed the point

No Garry, I think I understand the agenda. I believe it is a push for shallower stones for earing because they accumulate body oils easily, and while I''ll say I don''t know the answer because it will depend on the lighting and the baseline cut cut parameters.

While I could generate numbers, they may or may not give the "viewers perspective" that a reverse ray trace simulation like Sergeys would, that would probably correlate better to a controleed observational study. My simulations a more globa in nature, similar to the initial GIA WLR "brilliance" study, and are geared around a observational angle weighting function (which can be changed from the GIA cosine squared model I used in the 3D model in an attempt at an independent verification of GIA''s published data). In fact that was one of the few things I agreed with GIA on, they were on the right track.

Also their hemispherical lighting model was, in my opinion, wrong. And backtracking to the single face up view observational model was completely wrong, and inconsistent with the real world. I believe the probablistic viewing position would be more like a Poisson distribution for worn jewelry, for the wearer, and entirely different for the outside viewer.

Date: 12/20/2006 3:38:37 AM
Author: adamasgem
Dark Green is reflected ray
Light Green is refracted ray from internal to the diamond
RED is refracted light loss through the pavailion

Grease, cooking oil, body oil, all have about the same RI.
The red is the pavilion light loss..The increased light loss out of the pavilion is why diamonds get dull when they accumulate gunk on the pavilion of the stone.

CLEAN YOUR DIAMONDS.. NEED I SAY MORE..

Yes - you could do more - a lot more. Sure, if I had the time and funding.. I think I''ve done plenty already by giving people the tools..

Use your program to predict the best performing proportion sets for diamonds with greasy pavilions please. Send funding

For example you could try comparing a straight Tolkowsky with 40.25 pavilion and 41.25 degree pavilion with the same table and crown angle. First you have to agree on a lighting model...Diamond has its highest efficiency for light return with high angle lighting. Long ago I used the +/-25 degree angle of incidence from the table normal as a benchmark case to show the loss of light return efficiency, using an inplane 2D model.

 

[kenny]

This is fascinating.
(Personally I keep my stone immaculate.)

But I thought when viewing the stone face up that a dirty pavilion would not affect light return as long as everything above the girdle was clean.
I know someone who uses those alcohol wipes (used before an injection) to clean the top of his diamond several times a day.
He argues there is no need to clean the pavilion because it is a super Ideal cut round.

I think I am reading that dirt/oil on the pavilion helps light escape out the pavilion because it changes the refractive index of the interface between the diamond's pavilion and air.

Right?

 

[adamasgem]

Date: 12/20/2006 11:28:13 AM
Author: kenny

This is fascinating.
(Personally I keep my stone immaculate.)

But I thought when viewing the stone face up that a dirty pavilion would not affect light return as long as everything above the girdle was clean.
I know someone who uses those alcohol wipes (used before an injection) to clean the top of his diamond several times a day.
He argues there is no need to clean the pavilion because it is a super Ideal cut round.

I think I am reading that dirt/oil on the pavilion helps light escape out the pavilion because it changes the refractive index of the interface between the diamond''s pavilion and air.

Right?

Kenny You are partially correct. What actually happens is that a diamond/air interface has a much smaller critical angle cone for light loss than a diamond/grease interface, such that any internal light ray hitting a diamond/grease interface has a much higher probability of exiting the stone, instead of being totally internally reflected..

 

[kenny]

So a clean pavilion functions like a tighter seal for light?

(I'm always reaching for the most simple words.)

 

[adamasgem]

Date: 12/20/2006 11:56:50 AM
Author: kenny
So a clean pavilion functions like a tighter seal for light?

(I''m always reaching for the most simple words.)

You got it Kenny...

 

[RockDoc]

Maybe in more understandable layman''s wordings I''d describe it as follows, based on my observations and experience.



When you''ve gone to a clothing store, try on a suit ( or whatever ) and you stand in front of those 3 way mirrors, when you change the angle of the mirrors how it reflects changes as well.

You get the same effect when you change the angles of the pavilion or crown facets.


As to the "dirty pavilion" scenario.... think of coating the mirrors with soap, and imagine what you''d see.

If you coat the mirror you change the refraction to that of whatever is on it. If its clean you have the refraction of diamond. If it''s soap you get the refraction appearance of soap.

Marty''s Fire Performance invention, once it get produced will be an excellent method of being able to demonstrate this, as well as through the analysis of the fire/color appearance it shows to further split the hair with how well the diamond shows the dispersion.

Maybe Marty will post an image of it.... I know he''s done it before on the forum but being a compu grape, I am not sure how to link it. Worth looking at though.

Be curious to see how the Fire Performance Scope would image a diamond with soap on it

Rockdoc