How significant are the star facets and lower girdles info?

[JohnQuixote]

Date: 8/26/2005 4:53:08 PM
Author: Wink
In my next life I want to be born with a math computer chip in my brain and enough money to buy all the new toys!

You want to be Bill Gates?

 

[JohnQuixote]

OK. This is regarding reflector device analysis...

I've done some diagrams to illustrate what I said a couple of weeks ago about pavilion yaw being unobservable in the crown view due to obscuration.

We can debate the other reasons too, but this one is my harangue.

Date: 8/7/2005 8:37:10 PM
Author: JohnQuixote

Lightscope is unsuccessful for the same simple reasons other Gilbertson-based reflectors are.

FIRST: As mentioned, you can’t see it in the crown view, as the arrows camouflage what’s going on. The mains are dark due to obscuration and you can’t detect anything in them.

SECOND: What you think you’re seeing under the table could be any number of things. The simplest cause could be leveling of the diamond. It could be angle variance. It could be the diamond out of round or simple azimuth shift. To confuse the issue, the stars and the table itself reflect in the center of the image while the lower girdle divisions have multiple reflections. It is a jambalaya of different elements that are subject to tertiary reflections and distortions.

As for your reflector colors, slight hue changes within those double reflections could be due to tilt, the diamond out of round, patterning variation, angle variance or even a fingerprint on the light source. They may have nothing to do with azimuth shift and if they do there is no way to tell if they are some sort of ancillary yaw without first looking for primary yaw in the pavilion mains which is very simple to do with the H&A viewer.

So even assuming you have a 100% perfectly level diamond, these things still have multiple causes and multiple reflections. The thing we do know is that it’s not yaw.

Here are crown views for a diamond with 2 yawed mains (the ones with yellow on them).

On the left - let there be light! When in normal activity the mains are unobscured and illuminated. Pavilion yaw is 'in play,' and there are effects present.

On the right - When obscured, like when taking photos in a reflector device, light from directly overhead feeding the pavilion mains is blocked and they go dark. Pavilion yaw is no longer directly illuminated. You don't observe pavilion yaw or the effects.

 

[JohnQuixote]

These are hypothetical side views for the same diamond.

First, fully illuminated:

 

[JohnQuixote]

And now obscured, as it is in reflector photography.

 

[JohnQuixote]

So... Any yaw in the pavilion mains (the dark areas or 'arrows' in this photo) is obscured due to the nature of this kind of photography. That is why assessing details of main pavilion yaw should be done in the pavilion view with a H&A viewer, where you have no obscuration and complete reflective details.

 

[Serg]

re:
YAW is the RESULTANT EFFECT of azimuth shift, when the facet has been polished in an East to West or West to East direction.

Edge detection machines we are aware of do not take enough measurements to "see" facet yaw. Remember these devices measure only certain points and assume straight lines. When polishing a real life diamond there are deviations possible in places that the current machines do not measure: Their edge detection merely assumes a certain line is there thus the inability to see indented naturals and yaw.

Scanning machines would have to measure the slope at the following intervals (depicted by the orange lines) and calculate the difference in slope on that particular facet in the same manner as it calculates azimuth shift from its designated indexed position.
Let us understand that C is what the machines are measuring for slope. However they would have to measure the slope at just inside points A and B (not merely points A and B) as well as at C order to calculate the difference in slope at all of these – (1) Point A to B (2) Point A to C (3) Point C to B.

These additional slope measurements would be necessary in order to evaluate the amount of yaw caused by the azimuth shift – and by the way things were adjusted by the cutter. Remember, he did what he could to straighten things out which has disguised but not omitted the yaw.

Now if possible this would be easier on large facets but much more difficult on smaller surfaces.

Hi Brian,

It is wrong description of principal Helium work.( I do not know : Is right or wrong description for other scanners?) Such discrete method can not give accuracy for azimuth better than half step between two positions for measuring ( may be even 1 step)( Helium standard step is 0.9 degree. Could be in 2 times more or less) . Helium accuracy is better, and not depends directly from size of step. And Helium can build naturals more than 100 microns. Of course angle accuracy for such small facets is much worse than for standard facets( Firstly because I can not see important reason to increasing such accuracy)

 

[strmrdr]

hmmmm,
Im still digesting all this but one thing that is standing out what is the affect of yawed crown facets,LGF and other facets it would seem that it would not only be the pavilian mains that could be hard to cut and get yawed if they gave problems?

 

[strmrdr]

Second ? looking at the arrows in the h&a viewer and the IS image here:

Its obvious that the hearts are going to be messed up.
Iv noticed in the past that while its harder to see that you can usualy tell face up if the hearts are messed up in h&a images and IS images but even more so in the lightscope.

Post the double reflection wire frame picture from DC please side by side with the same specs with no yaw.
It is the one that matches the patterns showed on IS and lightscope shots.
If yaw can be seen there face up it can be seen in the other face up images to one extent or another.

 

[strmrdr]

Lets look at this one.
Nice image isnt it but lets look again.

 

[strmrdr]

ooohhh no Luke there are problems in the pattern!
Use the force Luke!

 

[strmrdr]

yep yep Luke the evil empire has distorted our hearts!

 

[strmrdr]

help Luke our arrows are distorting!!

 

[strmrdr]

It has nice yaw dont it :}

 

[strmrdr]

But hmmm it still does a pretty kick butt job of returning light.

Hmmm I wouldnt throw it off her finger.


Btw does digging thru hundreds of diamonds on Jon's website looking for one with yaw and finding one in his education section that he doesnt have for sale, that had to rate a .dmc file right?
HMMMMMM
I think these diamonds are allready getting rejected atleast Jon,Brian and Paul are anyway so we consumers can relax and enjoy the fireworks :}

 

[Shay37]

Storm, could you scroll up page 5 and see if I got it or missed it entirely? PLEASE, PLEASE, PLEASE. I apologize in advance for being a PITA.

thanks,

Shay

edited to put the right page #

 

[Shay37]

Storm, never mind. I see that John answered me on the previous page. See I told ya I was a PITA.

Shay

 

[strmrdr]

Date: 8/27/2005 5:29:37 PM
Author: Shay37
Storm, never mind. I see that John answered me on the previous page. See I told ya I was a PITA.

Shay

LOL keep askin questions its the only way to learn.
Iv been driving John and Brian and Jon nutz asking yaw
questions for a while now.

Anything that redirects light away from the camera will affect the photos in the b-scope report to some extent or another.
If you look at lightview 6 you can see something is going on with this diamond.
But it still has nice light return and fire.

 

[strmrdr]

One thing im starting to see is that yawing just one facet if the cutter tries to fix it throws off a lot more than just that facet.
And can throw the whole diamond off.

Would it be better from a performance standpoint to take a hit in meet point symmetry and not try and fix it or is hiding it the proper action?

 

[Serg]

Date: 8/27/2005 5:45:03 PM
Author: strmrdr
One thing im starting to see is that yawing just one facet if the cutter tries to fix it throws off a lot more than just that facet.
And can throw the whole diamond off.

Would it be better from a performance standpoint to take a hit in meet point symmetry and not try and fix it or is hiding it the proper action?

http://www.gemology.ru/cut/english/symmetry/10.htm

".... The question still not answered is what major and minor symmetry distortions are with respect to two types of consumer’s perception of diamonds. The first type concerns the visual perception of the optical properties of diamonds, such as Scintillation, Brilliance, and Fire. Those symmetry distortions leading to degradation of the optical properties of a diamond can likely be considered as «substantial» or, even better, as «distortions affecting its optical properties». The second type concerns the visual perception of the quality of diamond cutting performed by the manufacturer. We attribute this type to the following symmetry distortions: table inclination, table displacement, culet displacement, edge pointing error, and upper facets displacement with respect to the lower facets. The quality of a diamond with respect to the symmetry of this type is especially clear to an expert equipped with a loupe. A high expert’s grade of the skill of the manufacturer who has succeeded in the symmetric, almost ideal geometry of the stone can, of course, affect the price of the cut diamond. Such symmetry distortions, or rather their absence, can be considered as an «illustration of manufacturer’s skills» or «assembling quality».
"

 

[strmrdr]

Thanks serg am backtracking and reading the whole thing.
Know most of it but its good to get a refresher once in the while.

 

[JohnQuixote]

Date: 8/27/2005 7:41:20 AM
Author: strmrdr

hmmmm,
Im still digesting all this but one thing that is standing out what is the affect of yawed crown facets,LGF and other facets it would seem that it would not only be the pavilian mains that could be hard to cut and get yawed if they gave problems?

When the pavilion is blocked in 8 the graining will become obvious. Remember that in straightening up the yaw in the main gets disguised, so unless you have a badly grained diamond or an amateur cutter the answer is no.

Its obvious that the hearts are going to be messed up.
Iv noticed in the past that while its harder to see that you can usualy tell face up if the hearts are messed up in h&a images and IS images but even more so in the lightscope.

Post the double reflection wire frame picture from DC please side by side with the same specs with no yaw. It is the one that matches the patterns showed on IS and lightscope shots.
If yaw can be seen there face up it can be seen in the other face up images to one extent or another.

Maybe. Or is it tilt? Or is it out of round? Or is it an indexing issue? Why do that when looking at the pavilion answers all the questions? I am not sure what you are seeing in your examples. Is this a jedi mind trick or are you just a padawan?

Would it be better from a performance standpoint to take a hit in meet point symmetry and not try and fix it or is hiding it the proper action?

It’s all driven by $$$. Ex or Id symmetry = more $$$. There is no reward for absence of yaw – and plenty in straightening it out to try and fool the machines.

If helium isn't fooled so easily it could create increased demand for better precision in fine-make - as you said, some of us here have been beating that drum for some time.

Serg, thank you for commenting. Good to see you in this thread.

 

[strmrdr]

Ah sir John but the Jedi master could not the broken arrow mend.
The patterns between the arrows their own story do they tell.
Do listen you?

 

[JohnQuixote]

Date: 8/28/2005 12:49:02 AM
Author: strmrdr
Ah sir John but the Jedi master could not the broken arrow mend.
The patterns between the arrows their own story do they tell.
Do listen you?

Hehe.

Ah, listen I do... But you do not hear, youngling.

You’re looking at this as a guy who clicks buttons in software. What Brian did was to transcend that and treat the virtual as real. I think that’s a fundamental problem causing some communication dysfunction in this thread.

Sure, any of us could click the software by 2 degrees and put everything back to 0, but you can’t do that in the real world. In cutting when mistakes are made you have to take away more diamond to repair it. In order to straighten out a real diamond like that the whole pavilion would have to be re-done in 8 cut, so Brian left the main azimuth shift in the original position that Leonid placed it in.

Then he only made fixes that could be 'real.' That was the whole point, young jedi-to-be.

He treated the virtual model as if it were actual and broke no rules with wire-frame clicks. He took a diamond that would be considered poorly produced and showed you how to SAVE that diamond without losing a ton of weight.

When you think about it, it really is compelling, and the main point here. Those who don’t cut maybe didn’t get that. No problem, but it’s definitely worth a ‘kewl’ or two.

 

[strmrdr]

Ah but Sir John yes kewl it be that the weight was kept.
Which a real cutter would rush to do, when on a diamond cutting.
Thats kewl but the point not be.
Recut further it not, if it weight not make, got to $$ make.

The point, left signs face up and face down did the damage and the fix do.
The damage visible be, face up, as see plainly.

 

[strmrdr]

Iv been thinking about this.
When a yawed main is currected it throws other things out in the makup of the diamond as the cutter tries and save the diamond and get the id/id.
I think there is agreement on that?

In other words the mains arent the only thing getting distorted.
The DC images Brian presented clearly show this.
It is possible that the yawed facet will not show up by itself face up as being yawed but the effects on the surrounding facets will.
The arrow is clearly broken is it broke because of the yaw or because of the steps taken to get the id/id and hide the yaw?

The patterns of lights and darks are distorted in the arrows image and the IS image.
Same question is this caused because of the yaw or because of the steps taken to get the id/id and hide the yaw?

 

[strmrdr]

Next question:
could Jedi master the arrow save for a good sym. rating settle?
or is it gone too far?

 

[Garry H (Cut Nut)]

Well cut Brian.

Folks you can see the 4 lower girdle and the 1 main pavilion that has been reworked.

I have not checked back, but i think the crown has also been refacted slightly shallower to realign.

I would not reject this stone.

Intersting result for contrast.
DiamCalc likes the yawed stone best.

I have seen some very poor scans on stones submitted to AGS where the bad scan symmetry gets a better result for light performance than an excellent scan (ie bad symmetry performs better than excellent symmetry)

 

[belle]

Date: 8/27/2005 3:29:14 AM
Author: JohnQuixote
- I think you are very worthy of the gem file.

PM me and I'll get it to you.

i am not worthy
i am not worthy

(i'll take it though! thanks

)

Date: 8/27/2005 3:29:14 AM
Author: JohnQuixote
I looked at your adjustments. If you want to go much further here is a tip: Remember which is the most important view of all. It will reveal much. Do you still want to work on it some?

doh!!
hearts of course! i was so excited once i got all of my angles matched up, i did a quick check of the h&a view, the is view and the jewelry lights view to make sure all was good. i was so pleased with the results, i went back to the proportions page and took screen shots while still in wireframe. of course that doesn't tell the whole story!

(with that flub i deserve to have the gemfile gift rescinded)

 

[belle]

Date: 8/28/2005 1:48:16 AM
Author: JohnQuixote

Date: 8/28/2005 12:49:02 AM
Author: strmrdr
Ah sir John but the Jedi master could not the broken arrow mend.
The patterns between the arrows their own story do they tell.
Do listen you?

Hehe.

Ah, listen I do... But you do not hear, youngling.

You’re looking at this as a guy who clicks buttons in software. What Brian did was to transcend that and treat the virtual as real. I think that’s a fundamental problem causing some communication dysfunction in this thread.

Sure, any of us could click the software by 2 degrees and put everything back to 0, but you can’t do that in the real world. In cutting when mistakes are made you have to take away more diamond to repair it. In order to straighten out a real diamond like that the whole pavilion would have to be re-done in 8 cut, so Brian left the main azimuth shift in the original position that Leonid placed it in.

Then he only made fixes that could be 'real.' That was the whole point, young jedi-to-be.

He treated the virtual model as if it were actual and broke no rules with wire-frame clicks. He took a diamond that would be considered poorly produced and showed you how to SAVE that diamond without losing a ton of weight.

When you think about it, it really is compelling, and the main point here. Those who don’t cut maybe didn’t get that. No problem, but it’s definitely worth a ‘kewl’ or two.

after spending waaaaaay too much time clicking away and breaking every cutting rule out there while trying to 'fix' leonid's diamond, i totally understand what you are saying. it's not about what one can do with a click of a mouse on a virtual model....what matters is what you can actually do with a very expensive piece of rough, in hand at the wheel. what i was doing with diamcalc could not be done in real life (good thing....that stone was toast on more than one occasion!) it was fun playing with it though, i learned a lot about the way angles work together and how each facet can be tuned ever so fine (and not so fine!) to perfection. i have the upmost respect for brian and what he can do in real life. i will continue to play with diamcalc to try and learn what i can about the relationship of facets and their effects on a diamond, but i know that no matter how much time i spend on it clicking away with my mouse, without practical experience, i am no closer to being a cutter.

 

[BrianTheCutter]

Date: 8/29/2005 1:09:46 AM
Author: strmrdr
Next question:
could Jedi master the arrow save for a good sym. rating settle?
or is it gone too far?

Strm it is a fair question but not a fiscal priority. It makes economic sense to acquire id or ex meet sym, This is graded while optical is not. It is why I am working hard to bring these things to light.

The arrow could not have been saved without redoing entire pavilion in 8 cut.