Round Table: Best light conditions for Diamond Subjective performance comparison

[Regular Guy]

Date: 5/18/2009 5:05:31 PM
Author: oldminer
I don't think ImaGem has anything of a 'simlar problem' in its lighting model compared to Gemex. Both of these models are out in the public domain for examination and possibly there are others such as GIA's attempt with its Diamond Dock. Subjective grading is all well and good, but in these scientific days, we surely ought to be looking at objective grading and making the system well defined. Another subjective system on top of the existing color and clarity schemes will not make things much easier.

Dave, I don't know...I don't want to go into loop mode, as we've done before. But rather than responding to your follow up to my EEK face (it's not a smiley...), I'll fish out again your text, above, that I was motivated to respond to, and then post what will be one link, to a fairly long post, which you had initiated. All I typed into the search box was: Imagem. Some 300 posts come up, maxing out the system, and then on the first page of posts, I chose the one thread that was the most recent. On it, you do tend to be very reasonable, as you always are. I'll let anyone who wishes to review see if they also are curious why I go "eek" to what I've yellowed above...

 

[strmrdr]

Date: 5/18/2009 8:30:50 PM
Author: Regular Guy

What are your ideas on the perfect lighting to judge performance?

 

[Regular Guy]

Date: 5/18/2009 9:56:08 PM
Author: strmrdr

Date: 5/18/2009 8:30:50 PM
Author: Regular Guy

What are your ideas on the perfect lighting to judge performance?

Karl,

Sweet of you to ask...as I hadn't thought a lot about it. Now I did, and have two answers....

1) Can we set up a concept based on the Truman Show, inspired by Diamond Calc?

For example, in the contemporary thread initiated by David about why he loves 60/60s (and I think that thread inspired this one, right?)... we have Serg suggesting:

"David,
In Dialite( Diamcalc light model for gemological light ) your 60/61 diamond has DC light return 1.08( Bigger then Tolkowsky), 1.16 for Table( what is much bigger)

In Office light your 60/61 diamond has just 0.88( and 0.71 for table) what is much worse then Tolkowsky

what diamond is better for consumer"

Now...that is a powerful concept. It's at least a part of what diamondcalc can do, and I suppose it is designed to give you data on performance, based on virtualizing the environment, and giving you lots of "what if" data.

So, instead, how about actualizing the virtual environment. This will involve I don't know what technology, but effectively, you'd need to have something to the effect of an annotated dimmer switch, so that as you move the dial, and get described lighting envirnoments as your result, and see the diamond in the various environments.

Then,

2 a) as diamondcalc possibly already does, you'd quantify the results.

b) Finally, for those of us who would like to understand the likelihood of a person being exposed to a generic set of lighting environments, you'd quantify the likelihood of exposure to the frequency of the lighting environments, and weight the totals based on predicted frequency of exposure.

(edited to add...) This 2b part can be another powerful result. For those of us who do like to see things quantified...it does allow for the option of seeing one single number which is the result of a realistic representation of reality. It does harken to the HCA. In fact, I was about to say it is like the HCA this way...but the HCA already went there, and is some sort of manifestation of this idea at the outset, taking only a slightly different route.

With respect to 2b, although there may be variability that would need to be tied to the likelihood of exposures, i.e, fishermen in Alaska, versus office workers anywhere, maybe this part of the data would be more like the relationship between minor facets against major ones like crown & pavilion angles, i.e., not so much.

Overall, I don't know if such a model is that helpful, but it was sweet of you to ask.

 

[strmrdr]

RG I like the way you think....

I always thought the StormCA would be kewl...
input the percentage of time spent each day in different lighting catagories and the preferred shape and it makes suggestions of the exact configuration best for that mix of environments.

 

[Serg]

Date: 5/18/2009 7:21:29 PM
Author: strmrdr
Sergey,

Criticizing others thoughts without posting your own does not help.

Karl,

Do you want say what you do not see my own thoughts in my post where I showed REASONS of problems in DD and Gemex light schemas ?
Whose thoughts do you see in those post? Or Do you think any thoughts in these post?
Do you see many PS post with explanations REASONS?

 

[Rockdiamond]

A great conversation Storm- and also relevant to the other thread, as Ira mentioned.
I think one extremely important aspect is that the amount of light needed to get a good focus using a macro is impressive.
The quality of that light has a huge impact on how the photo will look.
To a certain extent, isn''t it more important to get that super close up focus, than trying to replicate room ( or other) lighting.
Of course, I''m thinking of how to show a single diamond, or item to the most representative manner.

If there was a way to standardize the lighting, it would theoretically level the playing field- is that your thought?

When the term "back lighting" is used- what type of apparatus does that?

 

[Serg]

Ira,

re:So, instead, how about actualizing the virtual environment. This will involve I don''t know what technology, but effectively, you''d need to have something to the effect of an annotated dimmer switch, so that as you move the dial, and get described lighting envirnoments as your result, and see the diamond in the various environments.

We tried to print spherical HDR panorama ( from real light condition what we could use in Diamcalc) on film.
there are two big problems:
1) to find relative cheap but bright , uniform and small light source
2) film has low dynamical range (1:50). We need 1:1000 at least.

May be we need use projector directly( through mirror)

 

[strmrdr]

Date: 5/19/2009 3:24:59 AM
Author: Serg
Ira,


re:So, instead, how about actualizing the virtual environment. This will involve I don't know what technology, but effectively, you'd need to have something to the effect of an annotated dimmer switch, so that as you move the dial, and get described lighting envirnoments as your result, and see the diamond in the various environments.


We tried to print spherical HDR panorama ( from real light condition what we could use in Diamcalc) on film.

there are two big problems:

1) to find relative cheap but bright , uniform and small light source

2) film has low dynamical range (1:50). We need 1:1000 at least.


May be we need use projector directly( through mirror)

Now we are getting some place, I wondered how something like this would work.
http://www.3m.com/mpro/about.html
More:
http://www.notebookreview.com/default.asp?newsID=4346

I had wondered about using film also.
So it is kewl that you tried it and found problems with it.

 

[strmrdr]

Date: 5/19/2009 12:37:16 AM
Author: Serg

Date: 5/18/2009 7:21:29 PM

Author: strmrdr

Sergey,


Criticizing others thoughts without posting your own does not help.

Karl,


Do you want say what you do not see my own thoughts in my post where I showed REASONS of problems in DD and Gemex light schemas ?

Whose thoughts do you see in those post? Or Do you think any thoughts in these post?

Do you see many PS post with explanations REASONS?

There is a difference in posting ideas for consideration and shooting down others ideas.
One is more productive than the other.

 

[Serg]

Karl,

Could you create something better without deep understanding previous attempts , without analysis of most critical mistakes?
Do you want repeat this mistakes again and again?


Scientific dispute is not possible without opponent.

Re: Or Do you think any thoughts in these post?

Sorry for misprint. Should be:
Or Do you see any thoughts in these post?

 

[strmrdr]

Date: 5/19/2009 4:50:19 AM
Author: Serg
Karl,


Could you create something better without deep understanding previous attempts , without analysis of most critical mistakes?

Do you want repeat this mistakes again and again?



Scientific dispute is not possible without opponent.


Re: Or Do you think any thoughts in these post?


Sorry for misprint. Should be:

Or Do you see any thoughts in these post?

I get where you are coming from and understanding what others did wrong is good.
What I am saying is looking at what others did wrong alone will not lead to the correct answer but thinking of other ways of doing it will.

 

[Serg]

Date: 5/19/2009 5:03:07 AM
Author: strmrdr

Date: 5/19/2009 4:50:19 AM

Author: Serg

Karl,



Could you create something better without deep understanding previous attempts , without analysis of most critical mistakes?


Do you want repeat this mistakes again and again?




Scientific dispute is not possible without opponent.



Re: Or Do you think any thoughts in these post?



Sorry for misprint. Should be:


Or Do you see any thoughts in these post?

I get where you are coming from and understanding what others did wrong is good.

What I am saying is looking at what others did wrong alone will not lead to the correct answer but thinking of other ways of doing it will.

re:what others did wrong alone will not lead to the correct answer

It is First step what you need do before you have chance to receive correct answer.

 

[strmrdr]

For example if people are going to compare a fixed sample of diamonds I feel it is best to mount them in heads which are on a bar covered by flesh colored material rather than using trays.
Trays are not real world.

 

[strmrdr]

Date: 5/19/2009 5:09:50 AM
Author: strmrdr
For example if people are going to compare a fixed sample of diamonds I feel it is best to mount them in heads which are on a bar covered by flesh colored material rather than using trays.

Trays are not real world.

or even better yet have the bar over changeable backdrops that the person viewing them can match to their skin tone.

 

[whatmeworry]

Date: 5/18/2009 1:50:33 PM
Author: QueenMum

Date: 5/18/2009 1:30:04 PM
Author: strmrdr
Name 4 of each you think should be used.

I will only name 2 lighting conditions:
1) Outside, blue sky, northern light without sun
2) Spot/halogen lighting (yes, like in a jewelry

)

I don't need the white neon lighting (used by all the people in the diamond business I met) to judge performance (but well to judge color).

4 viewing distances:
20, 35, 65 and 200 cm (last one only with spot lighting to judge fire intensity)

I completely agree with these two (diffused daylight and spot lighting) for a round brilliant. I would also add candlelight or some darkened environment. You should judge diamonds in an environment that makes you want to stare at them. Fluorescent office lighting? I find round brilliants to be mediocre performers in that environment. Why bother proving that a round brilliant is the best of the mediocre performers? There are plenty of posts where folks have told the lighting where they really enjoy their diamonds. Those are the lighting environments you should use for comparison. I don't think you'll find office lighting too many times on the list.

 

[Serg]

Date: 5/19/2009 5:14:15 AM
Author: strmrdr

Date: 5/19/2009 5:09:50 AM

Author: strmrdr

For example if people are going to compare a fixed sample of diamonds I feel it is best to mount them in heads which are on a bar covered by flesh colored material rather than using trays.


Trays are not real world.

or even better yet have the bar over changeable backdrops that the person viewing them can match to their skin tone.

It is good for comparison diamonds with similar girdle shape, when you can use same settings.
But if you need compare round and emerald you need use quite different settings what can significantly shift comparison results .
I have plan discuss it with Garry and Janak in Antwerp 3 weeks later .

 

[strmrdr]

Date: 5/19/2009 5:26:20 AM
Author: Serg

It is good for comparison diamonds with similar girdle shape, when you can use same settings.

But if you need compare round and emerald you need use quite different settings what can significantly shift comparison results .

I have plan discuss it with Garry and Janak in Antwerp 3 weeks later .

the same thing would happen on the finger so it is real world.
I would use something like 14k stuller x1 4 prong heads
Cheap and you don't have to worry about plating wearing off.

 

[Serg]

Date: 5/19/2009 5:34:44 AM
Author: strmrdr

Date: 5/19/2009 5:26:20 AM

Author: Serg


It is good for comparison diamonds with similar girdle shape, when you can use same settings.


But if you need compare round and emerald you need use quite different settings what can significantly shift comparison results .


I have plan discuss it with Garry and Janak in Antwerp 3 weeks later .

the same thing would happen on the finger so it is real world.

I would use something like 14k stuller x1 4 prong heads

Cheap and you don''t have to worry about plating wearing off.

In real world you can use different settings for Emerald, for each type settings you can receive new result your comparison.
what settings could be standard for CUT comparison?

 

[strmrdr]

Date: 5/19/2009 5:46:11 AM
Author: Serg



In real world you can use different settings for Emerald, for each type settings you can receive new result your comparison.

what settings could be standard for CUT comparison?

4 prong wg to fit the stone in my opinion would be the best option.
It is likely the most common in the real world.

 

[diagem]

Date: 5/18/2009 11:58:00 AM
Author:strmrdr
We haven''t done one of these in a while.

To get the conversation started.
My opinion there isn''t one lighting condition that covers all aspects of diamond performance.

You are correct..., the problem there are way too many variant lighting options out there + the fact that its extremely personal as to the individual who seeks that info.

Trying to reduce it to one will lead to false results.

And too many will result in confusion.

However there should be a few basic rules.
1: no back lighting
2: realistic environment behind the diamond.
3: realistic head shadow/obstruction


Discussion is open.

Whats do you mean when you write ''subjective'' performance?

I think lighting should be focused on just a few options (e.g. outdoor shade & sun + indoor bright & soft light) most consumers encounter every day.
And the lighting the trade is accustomed too for grading purposes. (which doesnt reflect what the consumers realy wants to see most of the times).

It needs to stay simple (I think).

 

[Serg]

I suggest:
1) Office type ( different artificial light + big windows)
2) Theater Type
3) Jewelery shop
4) Night Club
5) Outdoor city
6) Outdoor park with trees

 

[strmrdr]

I think there needs to be 3 categories with sub-categories

Work
-- office florescent
-- office mixed - w/windows

Home
-- ceiling illumination - including new tech where the ceiling is the light
-- table lamps
-- bathroom and chandelier - this would also cover work elevator.
-- candlelight

Outdoors
-- sunlight
-- car
-- park under trees

 

[oldminer]

When one grades color of diamonds the convention is to use a certain color temperature of diffused lighting on a neutral white background.

When one grades clarity, we say 10x binocular magnification with dark-field illumination.

When one is going to grade light performance, one must select a single, standardized lighting model which creates a common viewing environment. One that allows those diamonds which perform at high levels to score high and those diamonds which look badly to score low. Once you find such a working lighting environment, you grade ALL diamonds in this single environment. This is GRADING, not what a diamond looks like in every possible lighting environment.

Part of the beauty of diamonds is that they change their looks as lighting changes. You want to grade them in a lighting situation which serves to allow measurement of nuance changes in performance which can be subjectively confirmed by humen eye mass testing. A lot of this was done by GIA before they made their cut grades public and the same was done by ImaGem and probably by others involved in this pursuit.

To GRADE things we always pick a standardized environment, not multiple environments. We specify the environment and go about grading. If the grading meets the test of mass human testing confirmation, then you have a good model for continued use. This all has been done.

Sure, consumers might want multiple lighting performance tests. So long as the results have been well tested by mass human perception review, then it could be an added sales feature, but it is not needed for setting a grade.

 

[Serg]

Date: 5/19/2009 7:50:37 AM
Author: oldminer
When one grades color of diamonds the convention is to use a certain color temperature of diffused lighting on a neutral white background.


When one grades clarity, we say 10x binocular magnification with dark-field illumination.


When one is going to grade light performance, one must select a single, standardized lighting model which creates a common viewing environment. One that allows those diamonds which perform at high levels to score high and those diamonds which look badly to score low. Once you find such a working lighting environment, you grade ALL diamonds in this single environment. This is GRADING, not what a diamond looks like in every possible lighting environment.


Part of the beauty of diamonds is that they change their looks as lighting changes. You want to grade them in a lighting situation which serves to allow measurement of nuance changes in performance which can be subjectively confirmed by humen eye mass testing. A lot of this was done by GIA before they made their cut grades public and the same was done by ImaGem and probably by others involved in this pursuit.


To GRADE things we always pick a standardized environment, not multiple environments. We specify the environment and go about grading. If the grading meets the test of mass human testing confirmation, then you have a good model for continued use. This all has been done.


Sure, consumers might want multiple lighting performance tests. So long as the results have been well tested by mass human perception review, then it could be an added sales feature, but it is not needed for setting a grade.

re:To GRADE things we always pick a standardized environment, not multiple environments.

1) Sport car, Land Cruiser, Urban Cruiser,.. Could you Grade these car in one environment
2) Should we GRADE BEAUTY by single number? Is it possible? Do you know such example from other industry, life ..?
3)Should consumer, professionals test Brilliancy, Fire, Scintillation in ONE environment

Biggest disadvantage of current gemological grade, what gemologists grade what they can and how they can, instead what consumers need and want.

 

[Stephan]

Date: 5/19/2009 8:19:45 AM
Author: Serg
Biggest disadvantage of current gemological grade, what gemologist grade what they can and how they can, instead what consumers need and want.

Ditto!

 

[diagem]

Date: 5/19/2009 7:50:37 AM
Author: oldminer
When one grades color of diamonds the convention is to use a certain color temperature of diffused lighting on a neutral white background.

When one grades clarity, we say 10x binocular magnification with dark-field illumination.

When one is going to grade light performance, one must select a single, standardized lighting model which creates a common viewing environment. One that allows those diamonds which perform at high levels to score high and those diamonds which look badly to score low. Once you find such a working lighting environment, you grade ALL diamonds in this single environment. This is GRADING, not what a diamond looks like in every possible lighting environment.

Part of the beauty of diamonds is that they change their looks as lighting changes. You want to grade them in a lighting situation which serves to allow measurement of nuance changes in performance which can be subjectively confirmed by humen eye mass testing. A lot of this was done by GIA before they made their cut grades public and the same was done by ImaGem and probably by others involved in this pursuit.

To GRADE things we always pick a standardized environment, not multiple environments. We specify the environment and go about grading. If the grading meets the test of mass human testing confirmation, then you have a good model for continued use. This all has been done.

Sure, consumers might want multiple lighting performance tests. So long as the results have been well tested by mass human perception review, then it could be an added sales feature, but it is not needed for setting a grade.

Dave..., the title to this thread is:

"Round Table: Best light conditions for Diamond Subjective performance comparison"

Its not about grading.
A vendor who will have the right tools to present a Diamond''s visual/appearance which would reflect a close ''enough'' environment to the life style of the potential consumer, this would be a tremendous added value to both consumers and vendors alike.

 

[Garry H (Cut Nut)]

I go out for the evening and you guys go crazy posting good stuff!

For Next Diamond I suggest diamonds are set in plain ring settings that are removable from the mechanical rocking device inside the light box. The rings sould be (key) locked in place. They would be lined up so the diamonds are a few millimeters apart - but can be changed in order at an observers request.

In ND all 10 stones will be positioned so that they face to a single vantage point 14 inches (35cm) away so that at a glance one can see the face up view of all diamonds. In an even more idealised system the arc to vantage point could flex so that a radial focus of 25cm to 50cm would be possible. I think we can do it.

All the mountings I have made for our studies have been partially open 4 prong steel settings mounted on flesh coloured curved strips.
Here is one iteration

 

[diagem]

Date: 5/19/2009 9:06:04 AM
Author: Garry H (Cut Nut)

I go out for the evening and you guys go crazy posting good stuff!

For Next Diamond I suggest diamonds are set in plain ring settings that are removable from the mechanical rocking device inside the light box. The rings sould be (key) locked in place. They would be lined up so the diamonds are a few millimeters apart - but can be changed in order at an observers request.

In ND all 10 stones will be positioned so that they face to a single vantage point 14 inches (35cm) away so that at a glance one can see the face up view of all diamonds. In an even more idealised system the arc to vantage point could flex so that a radial focus of 25cm to 50cm would be possible. I think we can do it.

All the mountings I have made for our studies have been partially open 4 prong steel settings mounted on flesh coloured curved strips.
Here is one iteration

Should we expect the comeback of TLB''s and LB''s?

 

[oldminer]

Sergey, I am talking about "grading" not a final, personal judgment of "beauty". Please don''t confuse what I have said.

On the issue of Subjective Grading, it makes no sense to speak of it when we can grade objsctively while still retaining personal taste and budget in the final selection. We grade D color, but not everyone wants a D color. If we would accept objective color grading, there would be no change in the ability to choose, but we could choose with way more confidence. I see no difference in the argument and am not trying to take the thread off course. I am trying to remind people that subjective grading has been successful while leading to a lot of problems which objective grading could help solve.

 

[Serg]

Date: 5/19/2009 9:33:40 AM
Author: oldminer
Sergey, I am talking about ''grading'' not a final, personal judgment of ''beauty''. Please don''t confuse what I have said.


On the issue of Subjective Grading, it makes no sense to speak of it when we can grade objsctively while still retaining personal taste and budget in the final selection. We grade D color, but not everyone wants a D color. If we would accept objective color grading, there would be no change in the ability to choose, but we could choose with way more confidence. I see no difference in the argument and am not trying to take the thread off course. I am trying to remind people that subjective grading has been successful while leading to a lot of problems which objective grading could help solve.

Dave,

I did not understand your last post