Brilliance, Fire, Scintillation, what are correct definitions?

[Serg]

re:The biggest thing that the current definitions of brilliance leaves out is contrast against the background.
Which of these diamonds is brighter?


Karl, in definition for Human you do not need account background because human eye does it automatically

During calculations you of course need work with Brightness relative to human eye level adaptation.

DC does it. See example from DCcolor

 

[WinkHPD]

Date: 5/4/2010 3:41:21 PM
Author: Garry H (Cut Nut)
6am and off to gym

Too bad you answered your question so fast without giving any chance for discussion.

The Square stone is obviously not going to be any where near as good looking as the round. For one thing there is no good contrast pattern, so even what looks bright in the ASET is going to look fairly dull in real life and without the contrast it is not likely to have good scintillation either.

As such it is fairly easy for me to reject this diamond just on the ASET alone.

I do not understand why you feel these wonderful tools (ASET and Idealscope) will lead to a new generation of bad cutting?

They are not meant for creating cuts, they are meant for assessing the potential of the cuts that are available already.

Wink

 

[ChunkyCushionLover]

Date: 5/4/2010 10:29:41 AM
Author: Serg

There are two diamonds both of them are red in ASET/IS and have very high ( highest) Brilliance according ASG and Imagem definitions. But first shows a(random) single( but real) light source very often ( for example 1 time in average) and second shows the same single light source very rare( for example 0.2-0.5 in average)
do you know such diamonds? do you believe what such diamonds exist ?

First has high DETAS/ETAS, second Has low DETAS/ETAS.

No that is not a proper application of the AGS definition nor is it part of their definition for brilliance in that paper.

AGS simplifies by considering a hemisphere with centre at the girdle plane and they consider all light source paths to the diamond will intersect this hemisphere.
They introduce maps for each property that permit their evaluation, these maps are generated for various tilt positions of the diamond.

 

[Serg]

Date: 5/5/2010 12:14:24 PM
Author: ChunkyCushionLover

Date: 5/4/2010 10:29:41 AM

Author: Serg


There are two diamonds both of them are red in ASET/IS and have very high ( highest) Brilliance according ASG and Imagem definitions. But first shows a(random) single( but real) light source very often ( for example 1 time in average) and second shows the same single light source very rare( for example 0.2-0.5 in average)

do you know such diamonds? do you believe what such diamonds exist ?


First has high DETAS/ETAS, second Has low DETAS/ETAS.

No that is not a proper application of the AGS definition nor is it part of their definition for brilliance in that paper.

AGS simplifies by considering a hemisphere with centre at the girdle plane and they consider all light source paths to the diamond will intersect this hemisphere.

They introduce maps for each property that permit their evaluation, these maps are generated for various tilt positions of the diamond.

"Gem Brilliance - Gemstone brilliance refers to the ability of a stone to appear illuminated to an observer. For this to occur light must be
directed from the virtual facets to the observer’s eyes. .... For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,
the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes.

Brilliance [can be defined] as the percentage by area of such tiny prisms that can direct light to the observer’s eyes.

This definition is simple and does not intend to account for obliquity factors that could be included to account for differences in the relative position of facets or illumination conditions."

 

[ChunkyCushionLover]

Date: 5/5/2010 1:32:10 PM
Author: Serg

Date: 5/5/2010 12:14:24 PM
Author: ChunkyCushionLover

Date: 5/4/2010 10:29:41 AM

Author: Serg


There are two diamonds both of them are red in ASET/IS and have very high ( highest) Brilliance according ASG and Imagem definitions. But first shows a(random) single( but real) light source very often ( for example 1 time in average) and second shows the same single light source very rare( for example 0.2-0.5 in average)

do you know such diamonds? do you believe what such diamonds exist ?


First has high DETAS/ETAS, second Has low DETAS/ETAS.

No that is not a proper application of the AGS definition nor is it part of their definition for brilliance in that paper.

AGS simplifies by considering a hemisphere with centre at the girdle plane and they consider all light source paths to the diamond will intersect this hemisphere.

They introduce maps for each property that permit their evaluation, these maps are generated for various tilt positions of the diamond.

''Gem Brilliance - Gemstone brilliance refers to the ability of a stone to appear illuminated to an observer. For this to occur light must be
directed from the virtual facets to the observer’s eyes. .... For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,
the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes.

Brilliance [can be defined] as the percentage by area of such tiny prisms that can direct light to the observer’s eyes.

This definition is simple and does not intend to account for obliquity factors that could be included to account for differences in the relative position of facets or illumination conditions.''

What is wrong with that? (I want to understand where your opinion is the same and where it differs)
Tilt the diamond the area of the prisms changes.

I think their definition may be closer to yours if you reread the whole paper. There is nothing gained from nitpicking words or of a sentence taken out of context.

 

[Serg]

Date: 5/5/2010 2:04:26 PM
Author: ChunkyCushionLover

Date: 5/5/2010 1:32:10 PM

Author: Serg

Date: 5/5/2010 12:14:24 PM

Author: ChunkyCushionLover

Date: 5/4/2010 10:29:41 AM


Author: Serg



There are two diamonds both of them are red in ASET/IS and have very high ( highest) Brilliance according ASG and Imagem definitions. But first shows a(random) single( but real) light source very often ( for example 1 time in average) and second shows the same single light source very rare( for example 0.2-0.5 in average)


do you know such diamonds? do you believe what such diamonds exist ?



First has high DETAS/ETAS, second Has low DETAS/ETAS.

No that is not a proper application of the AGS definition nor is it part of their definition for brilliance in that paper.


AGS simplifies by considering a hemisphere with centre at the girdle plane and they consider all light source paths to the diamond will intersect this hemisphere.


They introduce maps for each property that permit their evaluation, these maps are generated for various tilt positions of the diamond.

''Gem Brilliance - Gemstone brilliance refers to the ability of a stone to appear illuminated to an observer. For this to occur light must be

directed from the virtual facets to the observer’s eyes. .... For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,

the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes.


Brilliance [can be defined] as the percentage by area of such tiny prisms that can direct light to the observer’s eyes.


This definition is simple and does not intend to account for obliquity factors that could be included to account for differences in the relative position of facets or illumination conditions.''

What is wrong with that? (I want to understand where your opinion is the same and where it differs)

Tilt the diamond the area of the prisms changes.


I think their definition may be closer to yours if you reread the whole paper. There is nothing gained from nitpicking words or of a sentence taken out of context.

Brilliance is not average brightness of pixels or percentage prisms ( what is SAME) neither for Face up nor for tilting positions.
tilting change nothing in definition what use any type LR as integral light, average brightness, percentage prisms ( it is just different words for same approach )

Did you read my discussion with Dave about difference between comics and cartoon ? It is answer for your questions

 

[Paul-Antwerp]

Date: 5/5/2010 10:56:12 AM
Author: Serg

Date: 5/5/2010 10:43:17 AM
Author: Paul-Antwerp
This is what I understand.

- In ASET/IS, you cannot see or judge Fire, nor Scintillation. I fully agree, and it is for me also one of the reasons why I describe them as rejection-tools.

- For Fire, both angular dispersion and the angular size of the light source and the relation between both are important. Absolutely, it makes the difference between observing a fiery colour or not.

Difficult to understand is:

- ''In an igloo, you cannot see scintillation.'' Considering that an observer (not wearing white clothing) is present in the igloo, does that mean that the ''sparkle'' (on/off-effect) of some virtual facets as you move the stone is not scintillation in your definition?

- ''Small angular size is good for Fire and for Scintillation''. I understand your point for Fire, but can Fire not be observed in an igloo? Me not understanding your statement for Scintillation is actually connected to my question above.

Live long,

Just ''On/off-effect '' is not enough for ''sparkles of light, flashes''. For Flashes you need light source with brightness much more bigger than level of your eye brightness adaptation what is not possible for igloo even if you are using tuxedo .

Let me think about this overnight.

How about my second question, can you observe Fire in an igloo?

Live long,

 

[Serg]

Date: 5/5/2010 3:00:41 PM
Author: Paul-Antwerp

Date: 5/5/2010 10:56:12 AM

Author: Serg

Date: 5/5/2010 10:43:17 AM

Author: Paul-Antwerp

This is what I understand.


- In ASET/IS, you cannot see or judge Fire, nor Scintillation. I fully agree, and it is for me also one of the reasons why I describe them as rejection-tools.


- For Fire, both angular dispersion and the angular size of the light source and the relation between both are important. Absolutely, it makes the difference between observing a fiery colour or not.


Difficult to understand is:


- ''In an igloo, you cannot see scintillation.'' Considering that an observer (not wearing white clothing) is present in the igloo, does that mean that the ''sparkle'' (on/off-effect) of some virtual facets as you move the stone is not scintillation in your definition?


- ''Small angular size is good for Fire and for Scintillation''. I understand your point for Fire, but can Fire not be observed in an igloo? Me not understanding your statement for Scintillation is actually connected to my question above.


Live long,

Just ''On/off-effect '' is not enough for ''sparkles of light, flashes''. For Flashes you need light source with brightness much more bigger than level of your eye brightness adaptation what is not possible for igloo even if you are using tuxedo .

Let me think about this overnight.


How about my second question, can you observe Fire in an igloo?


Live long,

It depends from Fire definition .
Early today?, I wrote:
"...... Before we agree in Brilliance I do not see reasons discuss others definitions.
.... I do not like discuss about Fire here( it is too complex issue) "

Please understand me, I am very tired from debuts on PS which are completely useless for me and my research. I happy to help but I do not like argue with anybody here.

 

[ChunkyCushionLover]

Date: 5/5/2010 2:14:52 PM
Author: Serg

Date: 5/5/2010 2:04:26 PM
Author: ChunkyCushionLover

Date: 5/5/2010 1:32:10 PM

Author: Serg

Date: 5/5/2010 12:14:24 PM

Author: ChunkyCushionLover

Date: 5/4/2010 10:29:41 AM


Author: Serg



There are two diamonds both of them are red in ASET/IS and have very high ( highest) Brilliance according ASG and Imagem definitions. But first shows a(random) single( but real) light source very often ( for example 1 time in average) and second shows the same single light source very rare( for example 0.2-0.5 in average)


do you know such diamonds? do you believe what such diamonds exist ?



First has high DETAS/ETAS, second Has low DETAS/ETAS.

No that is not a proper application of the AGS definition nor is it part of their definition for brilliance in that paper.


AGS simplifies by considering a hemisphere with centre at the girdle plane and they consider all light source paths to the diamond will intersect this hemisphere.


They introduce maps for each property that permit their evaluation, these maps are generated for various tilt positions of the diamond.

''Gem Brilliance - Gemstone brilliance refers to the ability of a stone to appear illuminated to an observer. For this to occur light must be

directed from the virtual facets to the observer’s eyes. .... For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,

the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes.


Brilliance [can be defined] as the percentage by area of such tiny prisms that can direct light to the observer’s eyes.


This definition is simple and does not intend to account for obliquity factors that could be included to account for differences in the relative position of facets or illumination conditions.''

What is wrong with that? (I want to understand where your opinion is the same and where it differs)

Tilt the diamond the area of the prisms changes.


I think their definition may be closer to yours if you reread the whole paper. There is nothing gained from nitpicking words or of a sentence taken out of context.

Brilliance is not average brightness of pixels or percentage prisms ( what is SAME) neither for Face up nor for tilting positions.
tilting change nothing in definition what use any type LR as integral light, average brightness, percentage prisms ( it is just different words for same approach )

Did you read my discussion with Dave about difference between comics and cartoon ? It is answer for your questions

From reading your comments re: cartoon versus comic, your position is that brilliance is a quantity that should be observed dynamically.
You are stating the sum of the static images even at small variations of tilt would still not equal that of what is dynamically viewed and that it varies with speed of tilt.

While I can see where that would apply to scintillation I''m still not sure why we see brightness and contrast dynamically unless the diamond is being moved.

In the AGS study they have also shown that the tilt angles do not have to be small as the appearance can be approximated by the sum of reasonably large changes in tilt angle. Observation of the changing appearance in the maps in various metrics illustrates this.

I beleive you are also stating that it is not the sum over the entire crown but that distribution is also important, however this becomes less important when one considers symmetry in addition to brightness and contrast.

In the AGS study they have also shown that the tilt angles do not have to be small as the appearance can be approximated by the sum reasonably large changes in tilt angle. Observation of the changing appearance in the maps in various metrics illustrates this.

 

[Karl_K]

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover

In the AGS study they have also shown that the tilt angles do not have to be small as the appearance can be approximated by the sum reasonably large changes in tilt angle. Observation of the changing appearance in the maps in various metrics illustrates this.

I do not agree that any such thing has been proven.
Take a virtual facet that is dark at 0 degree tilt and 10 degree tilt
It could have flashed light to dark 5 to dozens of times in that range of tilt which is great.
If it stayed dark the whole time then that diamond more than likely has issues.
The first 10 degrees of tilt are the most important and should be looked at in very small increments.
This is one thing I don't like about DC the smallest is 1 degree.

 

[ChunkyCushionLover]

Date: 5/5/2010 8:06:16 PM
Author: Karl_K

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover

In the AGS study they have also shown that the tilt angles do not have to be small as the appearance can be approximated by the sum reasonably large changes in tilt angle. Observation of the changing appearance in the maps in various metrics illustrates this.

I do not agree that any such thing has been proven.
Take a virtual facet that is dark at 0 degree tilt and 10 degree tilt
It could have flashed light to dark 5 to dozens of times in that range of tilt which is great.
If it stayed dark the whole time then that diamond more than likely has issues.
The first 10 degrees of tilt are the most important and should be looked at in very small increments.
This is one thing I don''t like about DC the smallest is 1 degree.

For AGS PGS can you list the tilt angles and weighting for each of the metrics? Its something I''ve asked and not had answered yet.

 

[Karl_K]

Date: 5/5/2010 8:12:54 PM
Author: ChunkyCushionLover
For AGS PGS can you list the tilt angles and weighting for each of the metrics? Its something I''ve asked and not had answered yet.

I haven''t heard any official answer on that.

 

[Garry H (Cut Nut)]

Date: 5/5/2010 11:49:55 AM
Author: Wink

Date: 5/4/2010 3:41:21 PM
Author: Garry H (Cut Nut)
6am and off to gym

Too bad you answered your question so fast without giving any chance for discussion.

The Square stone is obviously not going to be any where near as good looking as the round. For one thing there is no good contrast pattern, so even what looks bright in the ASET is going to look fairly dull in real life and without the contrast it is not likely to have good scintillation either.

As such it is fairly easy for me to reject this diamond just on the ASET alone.

I do not understand why you feel these wonderful tools (ASET and Idealscope) will lead to a new generation of bad cutting?

They are not meant for creating cuts, they are meant for assessing the potential of the cuts that are available already.

Wink

Sorry for that Wink, I also had to answer a friends email request at 5.30am (nod, wink).
You must have seen Sergey''s representation of the very complex process in this thread and others for how they design new cuts.
ASET is one of the tools used there - but there are more than a dozen other factors too. Some are more ''selection'' oriented.

It is possible to design a cut that face up in ASET has lots of red that has good contrast and scintillation simply because the area from 45 up to 85 degrees is all red. If you had an ASET with an additional band of orange in the middle of the red (easy to design in DiamCalc) then you would have a new tool to make it easier.

The point is, relying overly on just one or 2 of these tools (that BTW - I make and sell) is a wrong and bad approach.

We can see from how many years we have been trying to define these simple terms here on Pricescope, and other org''s work, that we still have no working simple definition that holds for all cases.

If we can all contribute and challenge Sergey''s positive attempt here, then we may well make a break through.

Understanding what any problem really is, that needs a solution, is often the most powerful step toward a solution (I nearly wrote ''Moving Forward'' - a term that drives me NUTS!).

Clearly we do not have that clear idea of what B,F and S are yet.

 

[Garry H (Cut Nut)]

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover


From reading your comments re: cartoon versus comic, your position is that brilliance is a quantity that should be observed dynamically.
You are stating the sum of the static images even at small variations of tilt would still not equal that of what is dynamically viewed and that it varies with speed of tilt.

While I can see where that would apply to scintillation I''m still not sure why we see brightness and contrast dynamically unless the diamond is being moved.

Here is a Gem Adviser for the Carre in the earlier example. Except i have modelled it in Igloo lighting with no observer. The only darkness comes from leakage. It has a couple % better light return than a tolk RBC in all instances.

Sergey can you please answer CCL''s query?

CCL I deliberately removed the AGS discussion. If we can invite rep''s from AGS to answer those questions it would be more appropriate - I bet they will also learn from the discussion.

Anyone who has DiamCalc should use it. Anyone without Gem adviser - get it free here:

http://www.octonus.com/oct/download/adviser_demo_down.phtml

Sergey could you also tell me why this stone has a poor result for whole crown darkzone tilting 30 degrees? It is mostly table and the reuslt seems wrong?

 

[ChunkyCushionLover]

Date: 5/5/2010 9:44:24 PM
Author: Garry H (Cut Nut)

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover





From reading your comments re: cartoon versus comic, your position is that brilliance is a quantity that should be observed dynamically.
You are stating the sum of the static images even at small variations of tilt would still not equal that of what is dynamically viewed and that it varies with speed of tilt.

While I can see where that would apply to scintillation I'm still not sure why we see brightness and contrast dynamically unless the diamond is being moved.

Here is a Gem Adviser for the Carre in the earlier example. Except i have modelled it in Igloo lighting with no observer. The only darkness comes from leakage. It has a couple % better light return than a tolk RBC in all instances.

Sergey can you please answer CCL's query?

CCL I deliberately removed the AGS discussion. If we can invite rep's from AGS to answer those questions it would be more appropriate - I bet they will also learn from the discussion.

Anyone who has DiamCalc should use it. Anyone without Gem adviser - get it free here:

http://www.octonus.com/oct/download/adviser_demo_down.phtml

Sergey could you also tell me why this stone has a poor result for whole crown darkzone tilting 30 degrees? It is mostly table and the reuslt seems wrong?

1GB of Vram and Gemadvisor tells me I don't have enough vram

. Hmmm gotta figure out a solution on that one.

AGS stuff sounds good no problem hopefully one of the authors of that paper wouldn't mind answering some questions.

 

[Garry H (Cut Nut)]

Date: 5/5/2010 10:53:24 PM
Author: ChunkyCushionLover

Date: 5/5/2010 9:44:24 PM
Author: Garry H (Cut Nut)

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover






From reading your comments re: cartoon versus comic, your position is that brilliance is a quantity that should be observed dynamically.
You are stating the sum of the static images even at small variations of tilt would still not equal that of what is dynamically viewed and that it varies with speed of tilt.

While I can see where that would apply to scintillation I''m still not sure why we see brightness and contrast dynamically unless the diamond is being moved.

Here is a Gem Adviser for the Carre in the earlier example. Except i have modelled it in Igloo lighting with no observer. The only darkness comes from leakage. It has a couple % better light return than a tolk RBC in all instances.

Sergey can you please answer CCL''s query?

CCL I deliberately removed the AGS discussion. If we can invite rep''s from AGS to answer those questions it would be more appropriate - I bet they will also learn from the discussion.

Anyone who has DiamCalc should use it. Anyone without Gem adviser - get it free here:

http://www.octonus.com/oct/download/adviser_demo_down.phtml

Sergey could you also tell me why this stone has a poor result for whole crown darkzone tilting 30 degrees? It is mostly table and the reuslt seems wrong?

1GB of Vram and Gemadvisor tells me I don''t have enough vram

. Hmmm gotta figure out a solution on that one.

AGS stuff sounds good no problem hopefully one of the authors of that paper wouldn''t mind answering some questions.

I forgot to add that you should make a movie in the Igloo lighting.

or titl the stone manually with your mouse.

Here is the aSET white which looks like the ASET black anyway - which you can see in Gem Adviser (the stone has diddly squat leakage).

 

[ChunkyCushionLover]

Date: 5/5/2010 11:33:58 PM
Author: Garry H (Cut Nut)

Date: 5/5/2010 10:53:24 PM
Author: ChunkyCushionLover

Date: 5/5/2010 9:44:24 PM
Author: Garry H (Cut Nut)

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover








From reading your comments re: cartoon versus comic, your position is that brilliance is a quantity that should be observed dynamically.
You are stating the sum of the static images even at small variations of tilt would still not equal that of what is dynamically viewed and that it varies with speed of tilt.

While I can see where that would apply to scintillation I'm still not sure why we see brightness and contrast dynamically unless the diamond is being moved.

Here is a Gem Adviser for the Carre in the earlier example. Except i have modelled it in Igloo lighting with no observer. The only darkness comes from leakage. It has a couple % better light return than a tolk RBC in all instances.

Sergey can you please answer CCL's query?

CCL I deliberately removed the AGS discussion. If we can invite rep's from AGS to answer those questions it would be more appropriate - I bet they will also learn from the discussion.

Anyone who has DiamCalc should use it. Anyone without Gem adviser - get it free here:

http://www.octonus.com/oct/download/adviser_demo_down.phtml

Sergey could you also tell me why this stone has a poor result for whole crown darkzone tilting 30 degrees? It is mostly table and the reuslt seems wrong?

1GB of Vram and Gemadvisor tells me I don't have enough vram

. Hmmm gotta figure out a solution on that one.

AGS stuff sounds good no problem hopefully one of the authors of that paper wouldn't mind answering some questions.

I forgot to add that you should make a movie in the Igloo lighting.

or titl the stone manually with your mouse.

Here is the aSET white which looks like the ASET black anyway - which you can see in Gem Adviser (the stone has diddly squat leakage).

0 Leakage from -15 to +15 degrees in tilt or is it -30 to +30 tilt.
Yeah I was able to make a virtual machine and get it to work .

Interesting so even over such a wide tilt range the carre is still gathering light from overhead over the whole range

.

The DMC file was of the round not the carre you meant to redo that one?.

 

[Garry H (Cut Nut)]

Sorry - I saved it as .dmc not .gem
Try this one

 

[Serg]

Date: 5/5/2010 9:44:24 PM
Author: Garry H (Cut Nut)

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover



From reading your comments re: cartoon versus comic, your position is that brilliance is a quantity that should be observed dynamically.
You are stating the sum of the static images even at small variations of tilt would still not equal that of what is dynamically viewed and that it varies with speed of tilt.

While I can see where that would apply to scintillation I''m still not sure why we see brightness and contrast dynamically unless the diamond is being moved.

Here is a Gem Adviser for the Carre in the earlier example. Except i have modelled it in Igloo lighting with no observer. The only darkness comes from leakage. It has a couple % better light return than a tolk RBC in all instances.

Sergey can you please answer CCL''s query?

Garry,
His question is not clear for me.

"I''m still not sure why we see brightness and contrast dynamically unless the diamond is being moved.
"

I did not say what we see brightness dynamicaly unless the diamond is being moved.
I said what motion is part of Brilliance.

Do you see difference between DC static images and DC movies from same static images?
DC static images are "Flat"( any life, Brilliance is absent in DC static image)
But Movie from Same "Flat" images has Brilliance !

Do you remember difference between between mono and Stereo( real Streo) DC movies ?
there is huge difference between stereo and static DC movies ( both from Same static images)
unfortunetely few people in world saw DC stereo movies. you can not explain this difference for person who did not see it

But difference between static DC image and DC movie could see anybody



CCL I deliberately removed the AGS discussion. If we can invite rep''s from AGS to answer those questions it would be more appropriate - I bet they will also learn from the discussion.

Anyone who has DiamCalc should use it. Anyone without Gem adviser - get it free here:

http://www.octonus.com/oct/download/adviser_demo_down.phtml

Sergey could you also tell me why this stone has a poor result for whole crown darkzone tilting 30 degrees? It is mostly table and the reuslt seems wrong?

Garry,
this cuts has very small crown. If you tilt French Carre on 25-30 degree then 25% crown has shtrong leakage
we use multiplication to receive "average " LR for tilting positions . LR=SQRT( a*b) instead (a+b)/2. So even one position with bad LR penalty whole grade. IF DarkZone is zero even for one diamond position, "Average"grade for 30 positions is zero too. for my opinion good LR from one position can not compensate bad LR for other position, your brain remember "something wrong with this diamond" even you saw problem just in one place

 

[Serg]

Date: 5/5/2010 8:06:16 PM
Author: Karl_K

Date: 5/5/2010 7:11:42 PM
Author: ChunkyCushionLover

In the AGS study they have also shown that the tilt angles do not have to be small as the appearance can be approximated by the sum reasonably large changes in tilt angle. Observation of the changing appearance in the maps in various metrics illustrates this.

I do not agree that any such thing has been proven.
Take a virtual facet that is dark at 0 degree tilt and 10 degree tilt
It could have flashed light to dark 5 to dozens of times in that range of tilt which is great.
If it stayed dark the whole time then that diamond more than likely has issues.
The first 10 degrees of tilt are the most important and should be looked at in very small increments.
This is one thing I don''t like about DC the smallest is 1 degree.

1 degree is smallest default angle.
You can use even 0.01

 

[Paul-Antwerp]

Date: 5/5/2010 3:32:51 PM
Author: Serg

Date: 5/5/2010 3:00:41 PM
Author: Paul-Antwerp

Date: 5/5/2010 10:56:12 AM

Author: Serg

Date: 5/5/2010 10:43:17 AM

Author: Paul-Antwerp

This is what I understand.

- In ASET/IS, you cannot see or judge Fire, nor Scintillation. I fully agree, and it is for me also one of the reasons why I describe them as rejection-tools
- For Fire, both angular dispersion and the angular size of the light source and the relation between both are important. Absolutely, it makes the difference between observing a fiery colour or not.

Difficult to understand is:

- ''In an igloo, you cannot see scintillation.'' Considering that an observer (not wearing white clothing) is present in the igloo, does that mean that the ''sparkle'' (on/off-effect) of some virtual facets as you move the stone is not scintillation in your definition?
- ''Small angular size is good for Fire and for Scintillation''. I understand your point for Fire, but can Fire not be observed in an igloo? Me not understanding your statement for Scintillation is actually connected to my question above.

Live long,

Just ''On/off-effect '' is not enough for ''sparkles of light, flashes''. For Flashes you need light source with brightness much more bigger than level of your eye brightness adaptation what is not possible for igloo even if you are using tuxedo .

Let me think about this overnight.

How about my second question, can you observe Fire in an igloo?

Live long,

It depends from Fire definition .
Early today?, I wrote:
''...... Before we agree in Brilliance I do not see reasons discuss others definitions.
.... I do not like discuss about Fire here( it is too complex issue) ''

Please understand me, I am very tired from debuts on PS which are completely useless for me and my research. I happy to help but I do not like argue with anybody here.

I understand your feelings, Sergey. Personally, I try to limit my time on PS too, scheduling short periods during the day and limiting posts to subjects that I consider useful.

Still, I tested some observations on stones in my office today. North-facing windows, complete overcast day, generally white office, except for a grey floor, no lights on. I observed white flashes and coloured flashes (the latter logically more when I took off my glasses).

Compared to the igloo-example, is this because of differences in brightness bouncing off from wall, floor, ceiling?

Live long,

 

[Serg]

Date: 5/6/2010 9:09:01 AM
Author: Paul-Antwerp

Date: 5/5/2010 3:32:51 PM

Author: Serg

Date: 5/5/2010 3:00:41 PM

Author: Paul-Antwerp

Date: 5/5/2010 10:56:12 AM


Author: Serg

Date: 5/5/2010 10:43:17 AM


Author: Paul-Antwerp


This is what I understand.


- In ASET/IS, you cannot see or judge Fire, nor Scintillation. I fully agree, and it is for me also one of the reasons why I describe them as rejection-tools

- For Fire, both angular dispersion and the angular size of the light source and the relation between both are important. Absolutely, it makes the difference between observing a fiery colour or not.


Difficult to understand is:


- ''In an igloo, you cannot see scintillation.'' Considering that an observer (not wearing white clothing) is present in the igloo, does that mean that the ''sparkle'' (on/off-effect) of some virtual facets as you move the stone is not scintillation in your definition?

- ''Small angular size is good for Fire and for Scintillation''. I understand your point for Fire, but can Fire not be observed in an igloo? Me not understanding your statement for Scintillation is actually connected to my question above.


Live long,

Just ''On/off-effect '' is not enough for ''sparkles of light, flashes''. For Flashes you need light source with brightness much more bigger than level of your eye brightness adaptation what is not possible for igloo even if you are using tuxedo .

Let me think about this overnight.


How about my second question, can you observe Fire in an igloo?


Live long,

It depends from Fire definition .

Early today?, I wrote:

''...... Before we agree in Brilliance I do not see reasons discuss others definitions.

.... I do not like discuss about Fire here( it is too complex issue) ''


Please understand me, I am very tired from debuts on PS which are completely useless for me and my research. I happy to help but I do not like argue with anybody here.

I understand your feelings, Sergey. Personally, I try to limit my time on PS too, scheduling short periods during the day and limiting posts to subjects that I consider useful.


Still, I tested some observations on stones in my office today. North-facing windows, complete overcast day, generally white office, except for a grey floor, no lights on. I observed white flashes and coloured flashes (the latter logically more when I took off my glasses).


Compared to the igloo-example, is this because of differences in brightness bouncing off from wall, floor, ceiling?


Live long,

North-facing window has brightness similar ( or even bigger) to Tube lights.

Ceiling near tube lights has usually( it depends from ceiling type, sometime tube lights do not illuminate ceiling surface directly) much bigger brightness than floor

usually your eyes adopted to floor or table brightness level which is much more low than sky brightness level

So in office ( turn of light but with north-facing window) you can easy see very bright flashes

 

[adamasgem]

Date: 4/29/2010 11:54:35 AM
Author: oldminer
Both of you guys are in denial. There are lighting models which people who have created light return measuring device have decided upon but there is no universal agreement as to what is the one, single best lighting environment to use. Using one which exists, such as ImaGem''s lighting model, does provide a consistent way to assess light return it the ImaGem lighting environment. The industry has not agreed on any standard model so we all wait for that day. Obviously light return from the crown of the diamond is measured by a camera or sensor located perpendicular to the diamond''s table, but can collect light from a certain angular relationship to the entire crown. Some obstruction, mimicking the head of the wearer is incorporated in the ImaGem model, but again, this is ImaGem''s approach and is not universal. Such a universal lighting model could be created, but who is in charge? We do have a problem in this regard in order to advance the scientific approach to solving the problem.
One need not ''grade'' diamonds with light return measurements. One can simply ''report'' the findings. Let consumers make their own choice. I don''t care if they choose high, medium or low, so long as they get information which helps them and is consistent and repeatable.

The body color issue is a real issue. No one has proposed a valid measurement of fire to date. The problem with light becoming slightly tinted in most diamonds is one key problem. Where do you draw the line for whiteness? Do you really have more fire in every tinted diamond than in white diamonds? Obviously the answer is no. Is the measurement of fire and the adjustment to body color a combined function? Is it worth the huge cost of programming to get a measure which means so little? Fire is way too flexible a measure to get busy with. It will not determine the quality of a diamond''s cut. Besides, all well cut diamonds have some fire. Few people would want more fire at the cost of less white light return or less overall brightness.

Karl has given the best clue yet. ''All light is colored'' ''White light does not exist'' This being the case, measuring fire is a wasted effort. Reporting it is present is sufficient.

Paul; My effort to keep the explanations short is part of the inadequate way we express ourselves here. There is so much to the process of measuring light return that I can''t hope to give complete responses, but that does not mean there are large loopholes in the scientific effort to date with measuring light return. Maybe, someday, you will have an opportunity to be in my area and to come see the solid work that has been done in this regard. It might help to convince you that quality efforts have been successful in being able to competently quantify light return in the correct manner especially suited for diamonds. Your top cut diamonds would score extraordinarily well and if the technology was adopted, it would help convince more people of the correctness of your cut approach.

Dave, perhaps you should READ my patent on the first page of my website, which shows that you can qualitatively photograph the ability of a diamond to produce fire (disperse white light), and then CORRECT your statements above.

Garbage cutting, garbage fire photos... direct correlation exists..

 

[Rhino]

Date: 5/5/2010 9:26:22 AM
Author: Serg

Date: 5/5/2010 8:48:00 AM
Author: Paul-Antwerp
Where I thought that I understood Sergey''s distinction between brilliance and scintillation two pages earlier, I now must say that I did not and do not.


Are you saying that in a light-environment with only secondary light sources, there is no scintillation?

Vice versa, in a light-environment without secondary light sources (If that exists), there is no brilliance?


Live long,

In Igloo you can not see Scintillation, under one spot light you can not see Brilliance, In ASET/IS you can not see Fire, Brilliance, Scintillation even if you are tilting diamond

a lot of primary light sources could be equally one secondary light. Light source angular size is important key for this approach
Both relation between angular dispersion and light source angle is critical for Fire and light angular size is important Brilliance. Small angular size is good for Fire and Scintillation but is bad for Brilliance

I totally get what you''re saying Sergey but you are limiting your definition of Scintillation to that of "sparkle" scintillation as observed in spot lighting.

In an igloo you can see scintillation but it will not be sparkle scintillation. Instead you will be observing what the labs are defining as "patterned scintillation" (as opposed to sparkle scintillation). Patterned scintillation is that observance of bright and dark reflections (static or dynamic) or what AGS simply defines as "contrast" and can only be observed in diffused type lighting environments (or an igloo). In the igloo you will primarily only observe brightness (reflections of white light) and the patterning will primarily be caused by head/body obstruction.

 

[Serg]

Date: 5/6/2010 2:56:47 PM
Author: Rhino

Date: 5/5/2010 9:26:22 AM

Author: Serg

Date: 5/5/2010 8:48:00 AM

Author: Paul-Antwerp

Where I thought that I understood Sergey''s distinction between brilliance and scintillation two pages earlier, I now must say that I did not and do not.



Are you saying that in a light-environment with only secondary light sources, there is no scintillation?


Vice versa, in a light-environment without secondary light sources (If that exists), there is no brilliance?



Live long,

In Igloo you can not see Scintillation, under one spot light you can not see Brilliance, In ASET/IS you can not see Fire, Brilliance, Scintillation even if you are tilting diamond


a lot of primary light sources could be equally one secondary light. Light source angular size is important key for this approach

Both relation between angular dispersion and light source angle is critical for Fire and light angular size is important Brilliance. Small angular size is good for Fire and Scintillation but is bad for Brilliance

I totally get what you''re saying Sergey but you are limiting your definition of Scintillation to that of ''sparkle'' scintillation as observed in spot lighting.


In an igloo you can see scintillation but it will not be sparkle scintillation. Instead you will be observing what the labs are defining as ''patterned scintillation'' (as opposed to sparkle scintillation). Patterned scintillation is that observance of bright and dark reflections (static or dynamic) or what AGS simply defines as ''contrast'' and can only be observed in diffused type lighting environments (or an igloo). In the igloo you will primarily only observe brightness (reflections of white light) and the patterning will primarily be caused by head/body obstruction.

Rhino,
re:In an igloo you can see scintillation but it will not be sparkle scintillation.

It is not Scintillation, It is Brilliance
I hope you did not yet read all posts here

 

[Garry H (Cut Nut)]

Date: 5/6/2010 10:52:36 AM
Author: adamasgem
Dave, perhaps you should READ my patent on the first page of my website, which shows that you can qualitatively photograph the ability of a diamond to produce fire (disperse white light), and then CORRECT your statements above.

Garbage cutting, garbage fire photos... direct correlation exists..

Hi Marty,
Any contributions to the current discussion would be welcome?
But BTW - Does a DiamCalc model replicate the same effects as your qualitative patented system?
I have attached an example below:

 

[Garry H (Cut Nut)]

Date: 5/6/2010 9:09:01 AM
Author: Paul-Antwerp

I understand your feelings, Sergey. Personally, I try to limit my time on PS too, scheduling short periods during the day and limiting posts to subjects that I consider useful.

Still, I tested some observations on stones in my office today. North-facing windows, complete overcast day, generally white office, except for a grey floor, no lights on. I observed white flashes and coloured flashes (the latter logically more when I took off my glasses).

Compared to the igloo-example, is this because of differences in brightness bouncing off from wall, floor, ceiling?

Live long,

Hi Paul,
Remember this simple test - you can easily judge the intensity as well as the color temperature of any light. The window on a cloudy day in Surat is far brighter than the overhead light. But even here today on a dull autumn Melb day the light from my window is far brighter than the office fluoro tube.

 

[Paul-Antwerp]

I remember the simple observation, Garry, but I fail to see the connection to Brilliance not to be defined as a stone''s ability to appear illuminated to an observer.

Live long,

 

[Garry H (Cut Nut)]

Date: 5/6/2010 9:09:01 AM
Author: Paul-Antwerp

Date: 5/5/2010 3:32:51 PM
Author: Serg

Date: 5/5/2010 3:00:41 PM
Author: Paul-Antwerp

Date: 5/5/2010 10:56:12 AM

Author: Serg

Date: 5/5/2010 10:43:17 AM

Author: Paul-Antwerp

This is what I understand.

- In ASET/IS, you cannot see or judge Fire, nor Scintillation. I fully agree, and it is for me also one of the reasons why I describe them as rejection-tools
- For Fire, both angular dispersion and the angular size of the light source and the relation between both are important. Absolutely, it makes the difference between observing a fiery colour or not.

Difficult to understand is:

- ''In an igloo, you cannot see scintillation.'' Considering that an observer (not wearing white clothing) is present in the igloo, does that mean that the ''sparkle'' (on/off-effect) of some virtual facets as you move the stone is not scintillation in your definition?
- ''Small angular size is good for Fire and for Scintillation''. I understand your point for Fire, but can Fire not be observed in an igloo? Me not understanding your statement for Scintillation is actually connected to my question above.

Live long,

Just ''On/off-effect '' is not enough for ''sparkles of light, flashes''. For Flashes you need light source with brightness much more bigger than level of your eye brightness adaptation what is not possible for igloo even if you are using tuxedo .

Let me think about this overnight.

How about my second question, can you observe Fire in an igloo?

Live long,

It depends from Fire definition .
Early today?, I wrote:
''...... Before we agree in Brilliance I do not see reasons discuss others definitions.
.... I do not like discuss about Fire here( it is too complex issue) ''

Please understand me, I am very tired from debuts on PS which are completely useless for me and my research. I happy to help but I do not like argue with anybody here.

I understand your feelings, Sergey. Personally, I try to limit my time on PS too, scheduling short periods during the day and limiting posts to subjects that I consider useful.

Still, I tested some observations on stones in my office today. North-facing windows, complete overcast day, generally white office, except for a grey floor, no lights on. I observed white flashes and coloured flashes (the latter logically more when I took off my glasses).

Compared to the igloo-example, is this because of differences in brightness bouncing off from wall, floor, ceiling?

Live long,

Paul you made this statement:
I remember the simple observation, Garry, but I fail to see the connection to Brilliance not to be defined as a stone''s ability to appear illuminated to an observer.

I think the answers are clear above? And added too by Sergey''s response to Rhino?
The differences in brightness are that you have a lot of scintillation in the office environ.

 

[Karl_K]

Date: 5/7/2010 9:24:10 PM
Author: Garry H (Cut Nut)
I think the answers are clear above? And added too by Sergey's response to Rhino?

Garry what does brightness have to do with it?
The main reason there would be flashes is that it is not a flat lighting environment.
The lighting would also be off axis which can create fire. (light hitting at an angle is more likely to be returned as fire)
Flat on axis lighting is what will produce little dynamic brightness or dynamic fire.
I am confused and I thought I was starting to follow what Serg was talking about.