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How significant are the star facets and lower girdles info?

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Date: 8/29/2005 4:53:32 AM
Author: 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)
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Garry and Belle thank you kindly good sir and madam.

In super symmetrical stones we do not think yaw will be of benefit. John Q has had interesting discussions with Martin Haske on this. Garry yes there are cases where we feel it may be additive rather than subtractive. There is much to explore.

Belle you are quick to understand and yes you are worthy. Just remember it''s all in the hearts.
 
Thank you Strm, for providing the opportunity to point out these problems with crown evaluation once again.

This thread is becoming overgrown with things already said, but not yet heard. Try not to be closed to these facts as I clarify once again the differences in reflector technology.

Crown versus pavilion assessment is old-hat to Diamond polishers. We used these means to assess cut while polishing a diamond long before Rhinos roamed the cities.
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One of the most important aspects we look for is the reflection of the table.

The issues are definitely not DiamCalc and definitely not helium. Helium is in my professional opinion the finest measuring device available today. I said this long ago after having the privilege of viewing it on my first trip to Moscow when I met Sergey, some months before the IDCC conference.

The issues here are the problems in these photographs. This INNACURATE reading into crown based reflector images and making claims that are not true gives consumers an obscuration of the truth. This is the point, so let’s start here with these images you kindly made available.

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You can see that there are huge differences between these two images. Why? They are the same diamond photographed by the same person, aren’t they?

Incidentally, this a very well-taken photo of the arrows view. It is extremely level which is difficult in any circumstance – even if one uses an upside-down technique so the diamond rests on glass - because the lens of the camera must be level too, and can still be off.

(A+B+D) Shafts do not line up on Ideal-scope image but do on the HA-scope image -will explain why later.

(C+F+G+E) Inverted V’s completely different in shape not uniform in Ideal-scope image but uniform in the HA-scope image- will explain why later.

I) Culet off center in Ideal-scope image.

H) Has nothing to do with anything except that it’s an inclusion (Strm, I don’t understand why you would point this out earlier unless you thought it was something else?).

02Differences.jpg
 
The end result gave us this wire frame. This definitely shows us that something is not level.

Either the diamond or the camera is not 100% level in order to give us a culet that is off centre. Or it has a tilted table (an effect explained well by Garry H
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).

I have no idea how these were shot so it has to be one of these scenarios to give us this result of an off center culet.

09wireimahhscimageLR10DR13.jpg
 
This is the same model, tilted using the numbers from above (All increments 0.1’ per click. 2 clicks anticlockwise rotations. 10 clicks leftward rotations and 13 clicks downward rotations).

The diamond is not the same proportions but you can see the effect such tilt has on any diamond. What appears to be symmetry or azimuth problems are only problems of how level the diamond is. You can attempt to read this for me but sorry I don’t buy it.

This is why we cannot judge these Symmetry anomalies from above in the crown view.

First: A leveling issue between viewer and stone.
Second: The doubling of reflections creates too much interference in distinguishing azimuth shift unless its major and involves a main pavilion angle.
Third: As John Q showed on the last page, anything we may try to detect in the main pavilion is obscured.


14isDCA_wtilt.jpg
 
wow. thank you brian, for taking the time to put together this masterful presentation. i''ll have to admit, some of the information posted earlier in this thread was a little hard for me to grasp, but your efforts here were logical, straightforward and easy to understand. i greatly appreciate your efforts in explaining it.
 
Brian,
Amazing work and pictures
 
Hi Brian,

Thank you kindly for the response and illustration. I wish I had known you were going to tear apart that image as I would have either confirmed or denied its centeredness with you and make the necessary adjustments to let you give a more proper critique.

I would have you know that your posting was not in vain though as that picture, which I took over a year ago isn''t perfectly centered as that is a stone I keep here for demonstrative reasons and it is still here in my store. Being that it is I retook the shot, perfectly centered and will illustrate and demonstrate my point and the fact that we can and have been photographing deviations in pavilion reflections in the east/west orientation which we can primarily see in the reflections of the lower halves (not the mains as John properly points out is impossible to detect and I agree, due to obscuration). I am collecting the graphics and will demonstrate my point both with images and hard cold numbers as well as we are now able to measure this phenomena as well as photograph it.

It may be a bit but I''ll respond as time allows.

Kind regards,
 
Hi Rhino. That image was placed in the thread by Strm to demonstrate your way of thinking and your approach so it seemed a perfect choice to demonstrate how these findings may be skewed if you will excuse the pun.
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My point again: It should not be necessary for you to confirm or deny centeredness and tilt here. It should not be necessary to scan a diamond to death and bombard everyone with numbers to understand what we are seeing.

This is why I say, again and again, there is too much going on in the convoluted crown view. Elegant and simple assessment of pavilion matters should be done in the pavilion view.
 
The cutters quiz.

Ladies and gentlemen I have presented reasons I believe azimuth shift and resultant yaw in the pavilion cannot be meaningfully assessed from a face up view. But perhaps there are great gemological experts out there with skills beyond the power of my simple cutter comprehension.
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To any such experts and to consumers alike I issue the following quiz challenge.

Let us see true expertise in analyzing reflector images. No numbers. No discussion of centeredness or tilt. Just simple and elegant analysis as we have come to enjoy from reflectors like ideal-scope for light return (thank you Garry!) and H&A viewers for construction. It is easy to have the numbers and know what’s there. Why? Because you have the numbers. That is the point. No numbers. Just your pure crown view reflector analysis, please.

Here is the quiz.

Rhino and anyone, please analyze these face-up views and indicate: Where is the azimuth shift that will have resultant yaw? For any who can get 5 of the 6 correct I will personally (not WF) send a gift card for your favorite cup of Starbucks.

BGQuizCompare.jpg
 
Gee whiz (or should I say quiz) Brian.
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I only got our Helium last week! Sergey has not waved his magic wand over my head to grant me all diamond knowledge during that time.
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What I have said is that we've been photographing east/west orientation shifts in the optical design (and have been observing and doing this since 2001). Only last week did we get a scanner that measures azimuth angles showing deviation from ideal and I've been noting a correlation between those measurents as compared to the optical design of the gemstones in the face up position as we observe it in LS technology. During the course of my personal studies over the past few years I have been noting these deviations for some time and I make it my business to study the optical design of gemstones and what measurements influence their differences but mostly how it translates to human observation/perception.

Up untiil last week I have been limited (mainly by measuring devices) how to correlate the numbers with the optical design to the point that I have been. Helium has now opened up a new world of parameters for me to investigate and correlate to optical design. A study that will be years in progress however I have already photographed and noted some of these correllatoins already which I am illustrating in an upcoming article on the subject. One week into my study DOES NOT make me an ultimate authority on the subject, not by a long shot. And to sit and point to what facets have enough azimuth to result in yaw is nothing short of a joke at this point especially since I am the only lab beside GIA and AGS that possess a Helium scanner in the US that is even studying this subject (that I know of) and can photograph at the level of detail we do.

I am happy to share my studies on this subject of east/west orientation and how we observe, photograph and measure it in the face up view but don't assume that I can sit there and tell you exactly what facets have enough shift in azimuth that results in yaw. In case you haven't read in any of my earlier responses you will take note that I DID NOT AND DO NOT DISAGREE THAT THE ASSESSMENT THROUGH THE PAVILION is in any way wrong. I have not disagreed with anything you or John had written regarding your studies so please understand I am not arguing that point at all.

My disagreement with you at this point is you don't seem to think I can observe the results of azimuth deviation through the crown. I know I can. At this point the burden of proof lies on me to prove my point. All I am asking for is some time to collect the necessary graphics and data to present my case. I apologize if I'm not responding as quickly as you like but I can only come onto the forum as time allows and our clients take preference. I know you understand. I will respond as soon as I possibly can Brian and I thank you for your patience. I know Garry and Belle are awaiting a response in another thread regarding interference colors ... so little time ... so much work.

Kind regards,
 
Okay,

Here is my response to your quiz Brian.

I dont know, I don't care.

Every single one of those stones will be gorgeous and 99 out of 100 people will not be able to visually distiguish one from the other assuming that they are the same size, color and clarity.

Let me count those who might be able to that I know.

Probably's (Okay, pretty darn near guaranteed, but I am not sure even the maestro's can discern these tiny differences with the unaided eye from the crown.)

Richard von Sternberg
Paul Slegers
Brian the Cutter

Maybe's

John Quixote
Jon at GOG
and a handful of others capable of visualizing and thinking in 3D, including Richard Homer who is a cutting genius although he does not cut diamonds.

Most of the rest of the world, myself included, will see only incredibly beauty in any of these stones. The hairs are getting awfully thin that you are all splitting, but I appreciate that someone has to split them. Split away, but PLEASE!!! do not throw the babies out with the shavings, these are incredible stones! (visually at least!)

Wink
 
John Q:
I just saw this thread and scanned it quickly. Thanks for the kind words. This is the first I knew that my picture of ''yaw'' had appeared anywhere. It was quite a challenge and I am pleased that it has been seen.
 
Date: 9/2/2005 5:46:27 PM
Author: Rhino

Gee whiz (or should I say quiz) Brian.
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I only got our Helium last week! Sergey has not waved his magic wand over my head to grant me all diamond knowledge during that time.
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Rhino, LOL. You should experience this live and up-close.
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It’s quiz central around here. It’s a great learning environment but humble pie is on my lunch menu sometimes.


What I have said is that we've been photographing east/west orientation shifts in the optical design (and have been observing and doing this since 2001). Only last week did we get a scanner that measures azimuth angles showing deviation from ideal and I've been noting a correlation between those measurents as compared to the optical design of the gemstones in the face up position as we observe it in LS technology. During the course of my personal studies over the past few years I have been noting these deviations for some time and I make it my business to study the optical design of gemstones and what measurements influence their differences but mostly how it translates to human observation/perception...
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Hold the phone. Ok. Put the helium scanner down and back away slowly...
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Say hello to Robert Frost: There are two roads diverging here.

Road #1: That Helium will show us wonderful things, possibly including yaw. There is no argument about this possibility – we agree (snaps for helium!). Let’s set it aside for a minute.

Road #2: Disagreement about whether one can assess pavilion construction from the crown view. THIS is the road less traveled by, and it is where we need to come to resolution.

All of the assessment Brian did on your images was completely without numbers or stats. The simple challenge is - can you do the same on his images without numbers and stats?

Rhino, what good are the numbers if you can't be sure of what you're seeing in the crown due to the other jambalaya? Take off le gadget hat for a minute and just look at the reflector images Brian posted. The point he makes is that you should be able to assess what is what WITHOUT having to scan it ‘to death.’ We should be able to read pavilion construction with a single simple, elegant image. We have it. It is the hearts, or pavilion view.

If you have to ASK whether the crown has tilt or not...if you have to ask whether the image was centered or not...if you have to ask if the diamond is out of round...what good is the image? Heck yes - then you might as well have all the numbers from helium, the lab report, a DiamCalc model and a fortune cookie.
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I am happy to share my studies on this subject of east/west orientation and how we observe, photograph and measure it in the face up view but don't assume that I can sit there and tell you exactly what facets have enough shift in azimuth that results in yaw. In case you haven't read in any of my earlier responses you will take note that I DID NOT AND DO NOT DISAGREE THAT THE ASSESSMENT THROUGH THE PAVILION is in any way wrong. I have not disagreed with anything you or John had written regarding your studies so please understand I am not arguing that point at all.

My disagreement with you at this point is you don't seem to think I can observe the results of azimuth deviation through the crown. I know I can. At this point the burden of proof lies on me to prove my point. All I am asking for is some time to collect the necessary graphics and data to present my case. I apologize if I'm not responding as quickly as you like but I can only come onto the forum as time allows and our clients take preference. I know you understand. I will respond as soon as I possibly can Brian and I thank you for your patience. I know Garry and Belle are awaiting a response in another thread regarding interference colors ... so little time ... so much work.

Kind regards,
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Ok. I see we agree that assessment of pavilion construction can be done through the pavilion (it’s all in the hearts). So the simple question at hand is this... Can you assess what it wrong in the pavilion of the subject diamonds Brian posted by looking through the crown?

If yes, just indicate where the problems are and you win a Starbucks drink.
If no, then all the crown images in the world plus 5 bucks will only get you a Starbucks drink.
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Maybe I am not seeing it your way - tell me if I’m not – but all you have to do is point out where the probs are in those diamonds? If not, can we agree that the pavilion view is the best (simplest) method for assessing pavilion construction?

Once we can agree on that we can move on to what, no doubt, will be very interesting reports from you on the things helium will show us.
 
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