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Old Sibelius
 
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Quote this post and reply to it Post#151 @ 11-24-02 , 04:02 PM


.http://www.diamondring.com/forums/a...=&postid=217214


Last edited by Sibelius : 11-24-02 at 04:04 PM.
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Quote this post and reply to it Post#152 @ 11-24-02 , 04:11 PM


If your eye is where the fire comes out the light source is in your belly.

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Re: You got it Dym :)
Quote this post and reply to it Post#153 @ 11-24-02 , 08:00 PM


Quote:
Originally posted by Garry Holloway
The same - 68% would exit in the opposite direction. Energy is neither created nor destroyed.


This is a very interesting concept. I thought that you would have had to recalculate the ray paths (AND percentages) using the reverse light path. I expected that a different distribution of percentages would result (of course still adding up to 100% - and conserving energy). I did not expect that the ray exiting the table would still be 68%!

For my peace of mind can you display the ray trace with the incident light entering the crown instead and show the percentages.

Also, I was initially concerned with the two faint rays exiting near the junction of the upper facet and table on the right side.

Could you similarly display the ray traces with the incident light following these two paths?

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Quote this post and reply to it Post#154 @ 11-24-02 , 08:10 PM


Quote:
Originally posted by Sibelius
If your eye is where the fire comes out the light source is in your belly.


My spatial orientation may not be that great but my estimate from his images that he will need to bob down to see the exiting light ray but leaving room for the entering light ray to pass the side of his body/head.

The only way we can reconstruct this image in 3-D is to have the third perpendicular view (a side view but rotated around 90 degrees). If you can demonstrate this than I will know what you mean Sibelius.

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Re: Permanent star :)
Quote this post and reply to it Post#155 @ 11-24-02 , 08:18 PM


Quote:
Originally posted by Garry Holloway
Try this one
6 inch head (150mm)
viewed from 12 inches, 1M and 10,000M 9the view from the moon would be the same).

(PS to understand this you will need to read a few of the posts on the previous page).


These images do prove that there is some change in black areas with different head position (just not the star - which remains constant). Is this because (as I have proposed before) that the light uncovered by the receding head lightens the darkened aread?

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Re: Tilting
Quote this post and reply to it Post#156 @ 11-24-02 , 08:29 PM


Quote:
Originally posted by Garry Holloway
When you tilt this class of stone with black the black dissapears, unlike the 45 degree pavilion angle that Serg calls class 1 nailhead.
When you tilt the stone in this class on Sergey's chart (C33 P40) you get a disappearing nailhead.

"<<<Does the purple arrow head and shaft represent fire? >>>"
Jonathons idea that these black bits are hot spots is unrelated to anything to do with the fact that the black head shadow comes and goes. Except that in the flood lit stone fire caan only be seen in the non washed out areas. I discuss this on www.diamond-cut.com.au.

Gemology.ru also has a detailed discussion of what causes fire and how we see it.


This really goes back to the original issue is why Jonathan reports seeing high light return in this area.

Clearly he observes this phenomenon. The question is why?

Do you think it is solely due to the backlighting from the B'scope? Or is there another reason? Is is drawing an incorrect association between his observation and the black arrows? After listening to everyone's arguments - I am surprised that the weaker backlit environment can produce such an overwhelming concentration of light exiting the crown.

The bottomline is WHY is Jonathan seeing what he is seeing?

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Ray trace
Quote this post and reply to it Post#157 @ 11-24-02 , 08:51 PM


Garry,

Could you do the ray trace for the two marked rays on the right side of the crown as if they were entering the opposite direction?

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Quote this post and reply to it Post#158 @ 11-24-02 , 08:55 PM


Quote:
Originally posted by Garry Holloway
no - i think it is because there is a small amount of refraction via the crown facet that gets split when you are miles away. But really dont you think it is an amazing concept that the star would still thoeretically be there?


Yes I do, but does this not suggest that as long as the head is bigger than the diamond then you will always get this effect?

Do you really need to stipulate the angle subtended by the perimeters of the head? Does 31 degreee or 24 degrees make any significant difference? Is it not the size of the head that matter?

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Ray trace paths
Quote this post and reply to it Post#159 @ 11-24-02 , 08:58 PM


Last one did not work - with diagram this time.

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Ray trace paths
Quote this post and reply to it Post#160 @ 11-24-02 , 09:01 PM


aaargh - can't get it to work.


See those two faint light paths on the right exiting the upper facet/table at an angle (not the perpendicular one). Could you model the two ray paths?

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Quote this post and reply to it Post#161 @ 11-24-02 , 09:03 PM


Use same parameters from original. Just reverse the paths. Reply at your convenience!

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Quote this post and reply to it Post#162 @ 11-24-02 , 11:34 PM


Garry,

Was that image for me?

I am not after that one. It appears that is the same image as previous but just zoomed out. I am happy about the parallel light paths - I need no further demonstration.

What I am after are the ray traces for angled light entering (not exiting) the junction of the table and upper facet on the right side (there are two of them - faint but visible) as seen in your previous image. I want you to reverse the ray paths using these as the path of the incident light. Do these rays emerge perpendicular to the table at 0% (based on you reversibility of magnitudes?)

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Quote this post and reply to it Post#163 @ 11-25-02 , 04:38 AM


Hi Dym,

What do you not undesrtand?
I put another example. This is my pic, not Jonathons.

This is screen capture of split view in DC.
Upper pic looks like there is good return upwards, but the other angl shows where the source is and where return goes.

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Quote this post and reply to it Post#164 @ 11-25-02 , 04:42 AM


Can't we give names or numbers to our pics? In a long thread like this it would help.

S

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Re: Re: lets try again
Quote this post and reply to it Post#165 @ 11-25-02 , 12:29 PM


Quote:
Originally posted by UltimateDiamondSite
Gary, I am trying to use real world examples friend. How many H&A diamonds are cut to the example you are providing here? To date my experience has shown none. If consumers are going to relate you comments use something more common to the market ... not Serg's example of 40.0 pavilion angles and 33.x crown angles. Most H&A's are not cut like the example you are giving, even some of the worse one's I've seen. That is a one in a million stone there. In case I'm wrong please tell me specifically what crown/pavilion/table data you are using to creat that model.


Peace,
Rhino


Dear Rhino,


I see that you did not understand the main conceptions that Garry and me are trying to explain here. I think this happens because you consider Garry's posts as a potential threat for your core business. If you could reject this point of view and look at what is happening here abstractedly from your business that you could not only obtain new knowledge but also use it for improvement of your business.

I cease to participate in this thread, I wrote enough as to allow all interested to begin thinking about it. I do not intend to convince everyone in my statements, my go is to give you a possibility to gain an understanding of the problem.

At Sibelius's desire I'll try to elucidate this problem on our site in a couple of weeks.

Thanks to all for the discussion, sometimes it was very interesting. Hope that GIA-AGS agents like it as well. Especially for agents - my suggestion for open public discussion still is in power. Hope that the leaders of your institutes will somewhen understand the usefulness of it for your institutes as well.

Rocdoc, you didn't guess again :-) The thread "Very brilliant or a dud?" has greater prospect. DC is a tool and efficiency of use of this tool strongly depends on your skills and particularly on how deeply you understand the all numbers in the OGI and Sarin reports. I hope someone will demonstrate the right use of the OGI report for that diamond. Of course I can do it myself but will it be right?

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Re: Why Brillianscope should fix the leakage problem
Quote this post and reply to it Post#166 @ 11-25-02 , 04:59 PM


Quote:
Originally posted by Garry Holloway
I will post this shot here again for Jonathon.

Note the 12% ray path exiting the stone. This is leakage. If a light source supplied light to the pavilion in this direction (like the dome of the BS) then 12% of this light would exit to the viewer (camera) as a dispersed ray (because it is being refracted at close to the critical aangle = max dispersion).

Sorry,

Getting the hang of 'netequiette'


From post 252.

You have a single ray entering the table on the left.

See how there are two faint further rays exiting the crown on the right (near the junction of upper facet and table)?

Can you now reverse each of the light paths and demonstrate the magnitude of light which would exit the table (in the same manner it entered)


Since this ray would be emegring off a back drop of an otherwise black pavilion main facet, the camera will detect pixels of color that would be measurable (given that they are not being swamped by white light, as Randy Wagner claims is the case and why he tels me there is no problem with the leakage and illumination from behind the diamond).

Now Jonathon could this explain why you think the black bits are hot spots from where color emerges?

Would you like to do some pavilion covering tests and confirm it for yourself, and maybe post the results (or do you need permission from Gemex?).


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Re: Why Brillianscope should fix the leakage problem
Quote this post and reply to it Post#167 @ 11-25-02 , 05:02 PM


Quote:
Originally posted by Garry Holloway
I will post this shot here again for Jonathon.

Note the 12% ray path exiting the stone. This is leakage. If a light source supplied light to the pavilion in this direction (like the dome of the BS) then 12% of this light would exit to the viewer (camera) as a dispersed ray (because it is being refracted at close to the critical aangle = max dispersion).

Since this ray would be emegring off a back drop of an otherwise black pavilion main facet, the camera will detect pixels of color that would be measurable (given that they are not being swamped by white light, as Randy Wagner claims is the case and why he tels me there is no problem with the leakage and illumination from behind the diamond).

Now Jonathon could this explain why you think the black bits are hot spots from where color emerges?

Would you like to do some pavilion covering tests and confirm it for yourself, and maybe post the results (or do you need permission from Gemex?).


Yikes,

Put last message within quote

Sorry,

Getting the hang of 'netequiette'


From post 252.

You have a single ray entering the table on the left.

See how there are two faint further rays exiting the crown on the right (near the junction of upper facet and table)?

Can you now reverse each of the light paths and demonstrate the magnitude of light which would exit the table (in the same manner it entered)

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Quote this post and reply to it Post#168 @ 11-26-02 , 01:55 AM


From this I conclude that you are saying:

1) Just as ray paths are reversible so that magnitude of corresponding exiting rays are reversible - if it leaves with x% one direction, it will will leave with x% in reverse. Therefore, there is no other possible ray that can enter the crown from an angle other than perpendicular to produce significant reflection in the faceup view.

2) The hot spots seen by Jonathan are purely related to an artifact from the backlighting of the B'scope. It has nothing to do with tilting diamonds, blackspot classes, headshadow distances, peripheral light sources.

I apologise if the thread has become tangled but all these concepts were flowing into each other and it was hard to separate them without relating it to something that was already mentioned.

Nevertheless, it does not help when you answer some of the questions posted but not others and I have to guess or speculate on how to bring all of these ideas together. That is partly the reason why I cannot get a coherent picture of what is going on. I may suffer from not having the all the basic principles in place but I think a lot of your statements have a level of presumed knowledge which are familiar to you but not others. Suitably chosen references at times to build up my level of understanding and fill the gaps would be helpful as we go along. However, I am not stupid and although I have not done maths and physics for a while, I feel I am quite capable fo understanding the science behind this, given the appropriate information.

I would appreciate some appreciation of both my sincerity and intelligence.

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