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Difference between Ideal scope/Brilliance scope and Light Performance grading.

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Ukieza

Shiny_Rock
Joined
Apr 15, 2005
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I have a question. I was thinking about this and trying to figure out what the difference is here. From my understanding, the brilliance scope and ideal scope grading put out by places like GEMEX is to grade the light performance. Is there anything else it does? So, with the new princess grading they have a grade on there for light performance. What''s the difference between that grading and the idealscope/brilliance scope?

Any help would be appreciated.

Thanks!
Ukieza
 
I have just published an article on this very subject and am awaiting our banner ad to be displayed. The article covers the new "light performance" grading standards (GIA/AGS) and how they correllate with all the technologies PS''ers have become familiar with (Ideal-Scope and all red reflectors, BrillianceScope, HCA, Isee2, Gem Advisor, etc.). I can''t link via the forum so I''ll send you a pm.
 
Hi Rhino,

I was wondering if you could pm me this link as well.
I am really pleased to see that GIA and AGS are describing light performance in their new certs.

36.gif
 
Ah, what a great segway into your article then huh? Thanks again!

Ukieza
 
Hmm, breifly reading the article leaves my question still open. How do the brilliance/ideal scope results compare to the AGS light preformance grading?

*continues to read article*
Ukieza
 
Okay, I was looking at this thread:
https://www.pricescope.com/community/threads/examples-of-new-ags-grading-reports-for-round-and-princess.28878/

Some of my answers are being answered in here. Thanks Rhino for your help! I''m going to be focusing my attention to the thread listed above.

-Ukieza
 
No sweat.

In brief. The metrics for light performance that AGS is looking at are ...

a. brightness (relating to the ability of the facets to reflect back the proper balance of lights/darks to the observer). In GIA''s system relates directly to contrast.
b. dispersion (relating to the amount and strength of colored light return as observed in direct light conditions)
c. leakage (whites as observed under red reflectors)
d. contrast (I have not ready any in depth information on how AGS is grading or observing contrast). Currently there are 2 schools of thought on the subject. One is the contrast between light return vs light leakage (Holloway/MSU) the other is the contrast between facets that are reflecting back light vs facets that are reflecting back darks (ie. head obstruction). GIA has sided with the latter view so at this point I''m not 100% sure where AGS is headed with this metric.

To expound a bit further...

Brightness is reduced in diamonds as the result of one of 2 things.
1. If the angles are such that they produce steep/deep combos resulting in excessive light leakage. Anything that''s leaking through the pavilion is not being returned to the eye. Hence reduced brightness.
2. If the angles are such that they produce shallow/shallow combos resulting in a reflection of too many darks and not enough lights.

With princess cuts #2 is generally not an issue as shallow/shallows can be more commonly found in rounds though it could be possible and in this case red reflectors would be a very good indicator of the better performing stones. Red reflectors are not the most effective tools for weeding out the shallow/shallow combos in rounds though.

For the most part and more pointedly to your question it would be my educated guess that the light performance reported on the AGS Reports will correllate with BrillianceScope data. I wouldn''t bank 100% on red reflectors correllating with all the metrics just yet as these images must also be properly interpreted for the correct amount of blacks/dark reds/light reds/whites.

Once I get some of the AGS ideal princess stones in my hands I''ll be able to give a more thorough analysis and explanation and clarify their position on contrast.

Hope that helps.
 
Date: 5/20/2005 3:00:09 PM
Author: Rhino

d. contrast (I have not ready any in depth information on how AGS is grading or observing contrast). Currently there are 2 schools of thought on the subject. One is the contrast between light return vs light leakage (Holloway/MSU) the other is the contrast between facets that are reflecting back light vs facets that are reflecting back darks (ie. head obstruction). GIA has sided with the latter view so at this point I'm not 100% sure where AGS is headed with this metric.
Click to expand...


Sir Rhino - I believe these two schools meet, in the sense that slight leakage at facet junctions enhances the effects of obscuration.

AGS has said they are concerned with "distribution of the contrast pattern produced by obscuration" which is in line with this way of thinking: A diamond with no pinpoint leakage may look the same as a diamond with slight pinpoint leakage in an illumination scenario where no obscuration occurs... But when obscuration occurs the one with pinpoint leakage has an enhanced distribution of contrast.
 
Date: 5/20/2005 4:16:53 PM
Author: JohnQuixote

Date: 5/20/2005 3:00:09 PM
Author: Rhino

d. contrast (I have not ready any in depth information on how AGS is grading or observing contrast). Currently there are 2 schools of thought on the subject. One is the contrast between light return vs light leakage (Holloway/MSU) the other is the contrast between facets that are reflecting back light vs facets that are reflecting back darks (ie. head obstruction). GIA has sided with the latter view so at this point I''m not 100% sure where AGS is headed with this metric.
Click to expand...



Sir Rhino - I believe these two schools meet, in the sense that slight leakage at facet junctions enhances the effects of obscuration.

AGS has said they are concerned with ''distribution of the contrast pattern produced by obscuration'' which is in line with this way of thinking: A diamond with no pinpoint leakage may look the same as a diamond with slight pinpoint leakage in an illumination scenario where no obscuration occurs... But when obscuration occurs the one with pinpoint leakage has an enhanced distribution of contrast.
Click to expand...
Has AGS came out and said that diamonds with more leakage will be rewarded with a higher contrast rating?
 
Have you not got and read the IDCC conference proceedings Rhino?
Yhe one that your wife should have made you attend?

The reason why i have the black background on one of the ideal-scope and the ASET photos is to show the distribution of contrast from leakage.
 
IDCC: Great reads on contrast on pages 11-12 (some Aussie bloke), 27 (Serg), and 54-55 (Michael Cowing - Rhino, I think that one is right up your alley).
 
Ok... you''re officially bookmarked. :) Do I get the IDCC stuff from your site?
 
Yep Rhino the IDCC proceeings have a link of the front page www.ideal-scope.com
And because you waited so long it is now 1/2 price
9.gif
 
As long as we're touting it here, those IDCC proceedings additionally include informative articles by such renowned Pricescopers as Brian Gavin (patterning: the forming and grading of Hearts & Arrows) and Garry Holloway (Interpreting Ideal-Scope Images).
 
Hi Rhino—guess you may have messed up in other ways as well. I attended the GIA talk at Tucson and they said the dark part of the contrast is caused by three things—leakage, head/body reflections, and reflections of dark objects surrounding the diamond. Sorry… but thought you should know.
 
Messed up? What in the world are you talking about? What exactly have I messed up?
 
Rhino--you said "Currently there are 2 schools of thought on the
subject. One is the contrast between light return vs light leakage
(Holloway/MSU) the other is the contrast between facets that are
reflecting back light vs facets that are reflecting back darks (ie. head
obstruction). GIA has sided with the latter view so at this point I''m
not 100% sure where AGS is headed with this metric."

GIA said it was both, not siding either way. Maybe I didn''t understand
you if that''s not what you meant. Then I am sorry for the confusion.
 
No probl computernut. I can understand what you''re saying and how you can see where you thought I may have messed up. I should have said more clearly what my view is of the subject. I''ve spelled out, in clearer terms here and would appreciate your input as well.
 
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