Round Table: Best light conditions for Diamond Subjective performance comparison

[strmrdr]

Date: 5/20/2009 4:22:18 PM
Author: Regular Guy


Take light performance. If data changes predictably with a change in environment, and the changing environment is substantive to the pattern of changing scores in light performance, doesn''t the changing light as environment need to become part of the evaluative set?

YES!!!!

RG you have a better handle on this than many experts.

As matter of fact when talking about diamond performance lighting and environment is the most important variable!!!

 

[diagem]

Date: 5/20/2009 4:01:42 PM
Author: oldminer



All technology improves over time, but it must enter the market a bit imperfect and then users along with technicians and inventors improve its performance levels. A machine to grade color currently cannot identify problem diamonds with 100 or 99 percent accuracy. Not yet. I think 95% to 98% is possible right now.

Dave...., does it make a difference (in accuracy) if the ''machine'' grades rough or polished?

 

[diagem]

Date: 5/20/2009 4:34:25 PM
Author: DiaGem

Date: 5/20/2009 4:01:42 PM
Author: oldminer




All technology improves over time, but it must enter the market a bit imperfect and then users along with technicians and inventors improve its performance levels. A machine to grade color currently cannot identify problem diamonds with 100 or 99 percent accuracy. Not yet. I think 95% to 98% is possible right now.

Dave...., does it make a difference (in accuracy) if the ''machine'' grades rough or polished?

Bumping this thread as I am realy interested in hearing more details on the highlighted text above...

Dave...., anyone?

 

[Serg]

Date: 5/21/2009 10:07:25 AM
Author: DiaGem

Date: 5/20/2009 4:34:25 PM

Author: DiaGem

Date: 5/20/2009 4:01:42 PM

Author: oldminer






All technology improves over time, but it must enter the market a bit imperfect and then users along with technicians and inventors improve its performance levels. A machine to grade color currently cannot identify problem diamonds with 100 or 99 percent accuracy. Not yet. I think 95% to 98% is possible right now.

Dave...., does it make a difference (in accuracy) if the 'machine' grades rough or polished?

Bumping this thread as I am realy interested in hearing more details on the highlighted text above...


Dave...., anyone?

DiaGem , What is accuracy, If for example ONE diamond could receive SI2, SI3, I1 in different Labs( I hope you believe me what one diamond theoretically could receive SI2 and I in one LAB, in any Lab and it depends from week day)?

I think it is wrong direction to develop color machine for Pavilion grading. Table Color grading is much more perspective for machine grading.
and such grading machine could be possible if you have absorption spectrum , but I do not know good way to receive correct absorption spectrum for any diamond . In semipolish stage it is easy task. May be it is possible for polished diamonds too.( for most common spectrum type)

 

[strmrdr]

Date: 5/21/2009 10:33:38 AM
Author: Serg

Date: 5/21/2009 10:07:25 AM



I think it is wrong direction to develop color machine for Pavilion grading. Table Color grading is much more perspective for machine grading.

You would be correct if we were talking about the color a consumer sees.
That is not what lab color grading is about.
The industry pushes and prices color as a measurement of rarity not apparent color.
To upgrade supposedly less rare colors based on cutting improving the face up apparent color is flat out wrong(deceptive) within the current system.
To go to a face up color system and keep it fair to consumers would take an entirely new view of diamond color and a new pricing model.

Would it be a better system, well it would be more real world anyway.

 

[diagem]

Date: 5/21/2009 10:33:38 AM
Author: Serg

Date: 5/21/2009 10:07:25 AM
Author: DiaGem

Date: 5/20/2009 4:34:25 PM

Author: DiaGem

Date: 5/20/2009 4:01:42 PM

Author: oldminer







All technology improves over time, but it must enter the market a bit imperfect and then users along with technicians and inventors improve its performance levels. A machine to grade color currently cannot identify problem diamonds with 100 or 99 percent accuracy. Not yet. I think 95% to 98% is possible right now.

Dave...., does it make a difference (in accuracy) if the ''machine'' grades rough or polished?

Bumping this thread as I am realy interested in hearing more details on the highlighted text above...


Dave...., anyone?

DiaGem , What is accuracy, If for example ONE diamond could receive SI2, SI3, I1 in different Labs( I hope you believe me what one diamond theoretically could receive SI2 and I in one LAB, in any Lab and it depends from week day)?

Believe you?? Unfortunately I live it daily. It depends on much lesser issues than which week day it is

.

I think it is wrong direction to develop color machine for Pavilion grading. Table Color grading is much more perspective for machine grading.
and such grading machine could be possible if you have absorption spectrum , but I do not know good way to receive correct absorption spectrum for any diamond . In semipolish stage it is easy task. May be it is possible for polished diamonds too.( for most common spectrum type)

Serg,

I have a problem with face up (Table) color grading only...

As example I take the Fancy color grading system in which I believe is partly wrong or not sufficient..., some grades do not reflect the true material color.
Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade.

I also think color grading should not be limited to table position only as we are hoping for innovation advancement in the designer cut arena.
True, the majority of Diamonds cuts are based on different table cuts..., but I envision the future might bring us new designer table-less cuts...

 

[Serg]

Date: 5/21/2009 2:49:06 PM
Author: DiaGem

Date: 5/21/2009 10:33:38 AM

Author: Serg

Date: 5/21/2009 10:07:25 AM

Author: DiaGem

Date: 5/20/2009 4:34:25 PM


Author: DiaGem

Date: 5/20/2009 4:01:42 PM


Author: oldminer









All technology improves over time, but it must enter the market a bit imperfect and then users along with technicians and inventors improve its performance levels. A machine to grade color currently cannot identify problem diamonds with 100 or 99 percent accuracy. Not yet. I think 95% to 98% is possible right now.

Dave...., does it make a difference (in accuracy) if the ''machine'' grades rough or polished?

Bumping this thread as I am realy interested in hearing more details on the highlighted text above...



Dave...., anyone?

DiaGem , What is accuracy, If for example ONE diamond could receive SI2, SI3, I1 in different Labs( I hope you believe me what one diamond theoretically could receive SI2 and I in one LAB, in any Lab and it depends from week day)?


Believe you?? Unfortunately I live it daily. It depends on much lesser issues than which week day it is

.


I think it is wrong direction to develop color machine for Pavilion grading. Table Color grading is much more perspective for machine grading.

and such grading machine could be possible if you have absorption spectrum , but I do not know good way to receive correct absorption spectrum for any diamond . In semipolish stage it is easy task. May be it is possible for polished diamonds too.( for most common spectrum type)

Serg,


I have a problem with face up (Table) color grading only...


As example I take the Fancy color grading system in which I believe is partly wrong or not sufficient..., some grades do not reflect the true material color.

Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade.


I also think color grading should not be limited to table position only as we are hoping for innovation advancement in the designer cut arena.

True, the majority of Diamonds cuts are based on different table cuts..., but I envision the future might bring us new designer table-less cuts...

Diagem, Table could absent. It does not matter. I mean what machine color grading need use consumer direction to observe diamond.
table-less diamonds could have better performance, but will such diamond practical ?
How does new Antwerp zero-table cuts looks?

re:Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade

If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,

See green point in Vivid Zone

 

[Serg]

Front Position in MagnaColorscope

Photo by Roman Serov, MSU

 

[diagem]

Date: 5/21/2009 3:24:16 PM
Author: Serg

Diagem, Table could absent. It does not matter. I mean what machine color grading need use consumer direction to observe diamond.
table-less diamonds could have better performance, but will such diamond practical ?
How does new Antwerp zero-table cuts looks?

How will machine figure out which direction of a "3D" Diamond the consumer observes? For example..., in extreme generic models with significant CH (eg >20% height) one of the important observation direction is the profile (sculpture effect)..., if the Diamond shows a genuine ''J-K'' body color (profile) and an ''H'' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?

re:Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade

Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue? I think not!

If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,

See green point in Vivid Zone

Here..., a zero-table (non-Antwerp

) cut....

 

[Serg]

Date: 5/21/2009 5:26:58 PM
Author: DiaGem

Date: 5/21/2009 3:24:16 PM

Author: Serg


Diagem, Table could absent. It does not matter. I mean what machine color grading need use consumer direction to observe diamond.

table-less diamonds could have better performance, but will such diamond practical ?

How does new Antwerp zero-table cuts looks?


How will machine figure out which direction of a ''3D'' Diamond the consumer observes? For example..., in extreme generic models with significant CH (eg >20% height) one of the important observation direction is the profile (sculpture effect)..., if the Diamond shows a genuine ''J-K'' body color (profile) and an ''H'' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?


re:Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade


Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue? I think not!


If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,


See green point in Vivid Zone

Here..., a zero-table (non-Antwerp

) cut....

Diagem,
thanks for very good questions. Specially I like "Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue?"

There are two "Colors"
1) Body what has strong correlation with absorption spectrum and diamond size. Such "Color" create "Rarity Value" for fancy color diamonds
2) Face-up what depends from absorption spectrum , diamond size AND CUT. Such "Color" create two Values : "Craftsmanship" and Color Performance for Consumer.

Grading report for fancy color diamonds needs have information about Rarity and Craftsmanship.

re: if the Diamond shows a genuine ''J-K'' body color (profile) and an ''H'' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?

I do not see any real problem. "Machine" could give grade from any direction. "Machine" even does not need rotate diamond for this /
Expert can not give facet-up consistency grade for colorless diamonds

 

[diagem]

Date: 5/22/2009 3:13:19 AM
Author: Serg

Date: 5/21/2009 5:26:58 PM
Author: DiaGem

Date: 5/21/2009 3:24:16 PM

Author: Serg


Diagem, Table could absent. It does not matter. I mean what machine color grading need use consumer direction to observe diamond.

table-less diamonds could have better performance, but will such diamond practical ?

How does new Antwerp zero-table cuts looks?


How will machine figure out which direction of a ''3D'' Diamond the consumer observes? For example..., in extreme generic models with significant CH (eg >20% height) one of the important observation direction is the profile (sculpture effect)..., if the Diamond shows a genuine ''J-K'' body color (profile) and an ''H'' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?


re:Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade


Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue? I think not!


If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,


See green point in Vivid Zone

Here..., a zero-table (non-Antwerp

) cut....

Diagem,
thanks for very good questions. Specially I like ''Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue?''

There are two (three) ''Colors''
1) Body what has strong correlation with absorption spectrum and diamond size. Such ''Color'' create ''Rarity Value'' for fancy color diamonds
2) Face-up what depends from absorption spectrum , diamond size AND CUT. Such ''Color'' create two Values : ''Craftsmanship'' and Color Performance for Consumer.
3) Hue (actually a subdivision of 1) !! There is clearly a difference in grade assignments to specific color hue''s.
I am guessing..., thats where GIA (does) consider the "Rarity Value" within the grade...., the quantity of color needed for a yellow to earn the magic "Fancy" name/grade is obviously much greater than the quantity a Pink or Blue is required.

Grading report for fancy color diamonds needs have information about Rarity and Craftsmanship.

Fully agree with you..., but then a problem arises when gemologists need to involve value in the grade! Contradiction?

re: if the Diamond shows a genuine ''J-K'' body color (profile) and an ''H'' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?

I do not see any real problem. ''Machine'' could give grade from any direction. ''Machine'' even does not need rotate diamond for this /
Expert can not give facet-up consistency grade for colorless diamonds

Serg..., I have not yet seen a machine that can accurately and consistently issue grades on Diamonds...., Polished or (semi) Rough...
And even if...., what then, average out the color-grades to set value? We are still subjective!

 

[Serg]

Date: 5/22/2009 5:45:21 AM
Author: DiaGem

Date: 5/22/2009 3:13:19 AM

Author: Serg

Date: 5/21/2009 5:26:58 PM

Author: DiaGem

Date: 5/21/2009 3:24:16 PM


Author: Serg



Diagem, Table could absent. It does not matter. I mean what machine color grading need use consumer direction to observe diamond.


table-less diamonds could have better performance, but will such diamond practical ?


How does new Antwerp zero-table cuts looks?



How will machine figure out which direction of a '3D' Diamond the consumer observes? For example..., in extreme generic models with significant CH (eg >20% height) one of the important observation direction is the profile (sculpture effect)..., if the Diamond shows a genuine 'J-K' body color (profile) and an 'H' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?



re:Not to mention the disparity between color type intensity grades. I dont believe it will be efficient for the consumer and at some instances even the trade



Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue? I think not!




If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,



See green point in Vivid Zone

Here..., a zero-table (non-Antwerp

) cut....

Diagem,

thanks for very good questions. Specially I like 'Does a GIA Fancy yellow have the same quantity (body or face-up) color as a Fancy pink or blue?'


There are two (three) 'Colors'

1) Body what has strong correlation with absorption spectrum and diamond size. Such 'Color' create 'Rarity Value' for fancy color diamonds

2) Face-up what depends from absorption spectrum , diamond size AND CUT. Such 'Color' create two Values : 'Craftsmanship' and Color Performance for Consumer.

3) Hue (actually a subdivision of 1) !! There is clearly a difference in grade assignments to specific color hue's.

I am guessing..., thats where GIA (does) consider the 'Rarity Value' within the grade...., the quantity of color needed for a yellow to earn the magic 'Fancy' name/grade is obviously much greater than the quantity a Pink or Blue is required.



Grading report for fancy color diamonds needs have information about Rarity and Craftsmanship.



Fully agree with you..., but then a problem arises when gemologists need to involve value in the grade! Contradiction?


re: if the Diamond shows a genuine 'J-K' body color (profile) and an 'H' faceup color..., which is what?? What should the consumer pay for? Who owns the right to call the grade, a GG or the machine?


I do not see any real problem. 'Machine' could give grade from any direction. 'Machine' even does not need rotate diamond for this /

Expert can not give facet-up consistency grade for colorless diamonds


Serg..., I have not yet seen a machine that can accurately and consistently issue grades on Diamonds...., Polished or (semi) Rough...

And even if...., what then, average out the color-grades to set value? We are still subjective!

If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,

Daigem,
In beginning I did strong point, I FIXED HUE!!

 

[diagem]

Date: 5/22/2009 6:05:05 AM
Author: Serg


If we speak about grading for fancy color( for fixed Hue) , I think it should be point on 2D map( Chroma, Brightness ) ,

Daigem,
In beginning I did strong point, I FIXED HUE!!

I get it...

But like I said before....

I have not yet seen a machine that can accurately and consistently issue grades on Diamonds...., Polished or (semi) Rough...
And I have not seen an issued grading report that fixed the disparity of hue.