DiamCalc Anyone ?

[Iceberg]

Hi Rhino. The two GCAL reports I uploaded are for two diamonds of the same cut quality (IDEAL 0).

My question was/is: Why is it that 99.999% of all the other optical symmetry analysis reports I have seen DO NOT depict these prominent RED lines. All others are thin black lines as spokes of a wheel (like my brand new diamond).

I have looked at over 50 reports of AGS 000 grade diamonds and none showed RED lines.

WHY ?? Moreover, on the HCA scale, that diamond scored a 2. Consequently, with the RED lines , the crappy HCA score AND no one to giving me a response, I got rid of the diamond.

The red lines are so unusual and unique....????????

Paul

 

[Iceberg]

I almost forgot.

The diamond I got rid of had had a old AGS version so, I figured that, maybe, it possibly would not of made the cut with the new AGS report (which includes light).

It seemed that nothing was in the diamond''s favor.(HCA, odd depiction in the symmetry, noone answered, old version of the AGS grading report). I wanted peace of mind !!!

I now feel much better...MUCH.

Nevertheless, I am still puzzled as to why them red lines were so prominent. Ask around. The reports show (the majority of the time), thin black lines.

Hope I am clear in my explanations as English is not my first language (I''m French from Canada). 5 hours away from New York.

Paul

 

[Rhino]

Hi Paul,

Running in and out today ... (my days off wife finds errands ).

I realize your question did not pertain to optical symmetry really but the colors produced by the symmetry images. One being red the other black, particulalry on the "arrows".

This would have to do with the angles (both pavilion and crown) that the diamonnd was cut to. I see the GCAL standard for *excellent* has black arrows while the one in the 2nd pic you posted of the older stone had red. This would entirely relate to the angular spectrum that Don is using in his reflector photography. Certain combinations of crown/pavilion angles will draw light from different direction depending upon the angles they are cut too. To understand "angular spectrum" in more detail an brief explanation of AGS'' new ASET scope might help although not fully because we do not know the angular spectrum used by GCAL.

Ok... angular spectrum ... in brief (fellow Gmen help me out here if you see this explanation is not simple enough).

In AGS A.S.E.T. (angular spectrum evaluation tool) 3 primary colors are used. Green, red and blue.

I want you to think for a moment ... you standing in a regular room ... normal lighting from above ... the diamond held down before your eyes about a half an arms length distance in front of you.

The facets of the diamond reflect the panorama that is before it including

a. reflections from the hemisphere (walls, areas of non direct or weak light sources, etc.) This area covers approx. the 0 to 45 degree zone and is the source of weakest light.
b. reflections from above (primary source of bright light) 45-75 degree above the hemisphere
c. reflections directly from above ... ie your head and body which are blocking light. Covering the 75-90 degree zone.

a. b. and c. represent the typical angular spectrum before the diamond being observed.

In an ASET scope this angular spectrum is represented by colors.

a. = green
b. = red
c. = blue

There''s more to this but these are the basics. What''s desired is the best balanced combination of reds and blues with as little green as possible.

So in order to know and understand''s GCAL''s color scheme we would have to know which colors represent his particular angular spectrum.

Red reflectors are fairly straight forward. 0-75 degrees covered in red, 75-90 in black (or pretty darn close to this).

I''ll see if I can''t contact Don when I get back to work and find out what he has to say.

Peace,
Jon

Sir John Quixote ... do you have that ASET graphic handy? I don''t have it on my home laptop.

 

[JohnQuixote]

Date: 9/11/2005 6:59:39 PM
Author: Rhino

Sir John Quixote ... do you have that ASET graphic handy? I don''t have it on my home laptop.

(up periscope)

Rhino - I''ve been on a bit of PS-leave lately due to projects surrounding my eyeballs, but will gladly point in the direction of this thread in the FAQ. That should have the graphic you''re thinking of - along with several others.

(down periscope)