Azimuth Shift & Yaw

[beryl]

Rhino:
Yes, I am 'splitting frog hairs'. That is how I feel about 'errors' which may occur in readings by machines such as Sarin, Ogi, etc. Don't pursue this any further on my account.
Recall that this thread was created only to clarify the difference between azimuth shift and 'yaw'; I think that has been done.
Garry's example shows another important point - the person using the machine must instruct it and interpret its information correctly.
Beware of instruments - they can be helpful or misleading. Use your eyes and common sense also. A diamond that looks good IS good. Data are useful only for remote evaluation or appraisal.

BTW: I did not recognize that '.dmc' meant a DiamCalc file; 'computerese' frightens me. I have DiamCalc - a gift from Sergey; in fact, some of the features in it were my contributions. I also have H&A viewer - a gift from Brian. I have IdealScope - a gift from Garry, and its light source - a gift from Lieve Peeters and Paul Slegers. I have ASET - a gift from Peter Yantzer. Do you have 'Gemshape/Facet Designer' by Anton Vasiliev? If not I will send it to you and demonstrate it when we get together - perhaps in the FoodCourt at the Casino of the Sky some Wednesday.

I just noticed your ad at the top of the page. 'Square Hearts & Arrows' ! That interests me.

 

[JohnQuixote]

Date: 9/11/2005 12:44:52 AM
Author: beryl
Rhino:
Yes, I am 'splitting frog hairs'. That is how I feel about 'errors' which may occur in readings by machines such as Sarin, Ogi, etc. Don't pursue this any further on my account.
Recall that this thread was created only to clarify the difference between azimuth shift and 'yaw'; I think that has been done.
Garry's example shows another important point - the person using the machine must instruct it and interpret its information correctly.
Beware of instruments - they can be helpful or misleading. Use your eyes and common sense also. A diamond that looks good IS good. Data are useful only for remote evaluation or appraisal.

BTW: I did not recognize that '.dmc' meant a DiamCalc file; 'computerese' frightens me. I have DiamCalc - a gift from Sergey; in fact, some of the features in it were my contributions. I also have H&A viewer - a gift from Brian. I have IdealScope - a gift from Garry, and its light source - a gift from Lieve Peeters and Paul Slegers. I have ASET - a gift from Peter Yantzer. Do you have 'Gemshape/Facet Designer' by Anton Vasiliev? If not I will send it to you and demonstrate it when we get together - perhaps in the FoodCourt at the Casino of the Sky some Wednesday.

Bruce,

Sage advice. The 'eyes' always have it. Always good to have a reality check. My pricescope involvement has been extremely limited for the last week or so, but I've been skimming this thread as time permits - thank you for elaborating. Your drawings are remarkable as usual.

Say Rhino - Maybe your gift to Bruce should be a helium scanner.

 

[Rhino]

Date: 9/10/2005 8:55:41 PM
Author: Garry H (Cut Nut)

Date: 9/10/2005 8:11:48 PM
Author: Rhino
Heh... that''s cause Garry probably responded after having a little vino.

You''r on the money Rhino
it was late Friday night after our traditional Japanese dinner with friends

Do I know you Garry or what?

Hey ... I''m typing out a letter here on this laptop and was recalling what I think is perhaps the very first time we exchanged dialogue. Do you recall a thread about "the bowtie of a marquise"? This is pre-pricescope and even pre-idealscope days. Everyone in the thread was accounting it to light leakage (LOL... if I recall RockDoc wasn''t even sure) and I stood alone in that thread trying to convey the phenomena i was seeing through the FireScope. I had deduced that it definitely was not leakage, but that those facets were functioning as reflectors (reflecting back the shadow of the eye). The reason this stands out in my mind is becuase, if I remember correctly, you were the only one who stood with me while the eggs were being thrown and I was being publicly ridiculed. Time and science has proven who was correct but since that day I had always felt a certain kinship with ya.

Just thinking out loud here but thought I''d share that. Do you remember that thread?

All the best,

 

[beryl]

Edit: Deleted - forgot pic. Text duplicated below with illustration.

 

[beryl]

I don't yet know how diamond scanners work, but this shows what they see if looking at a profile, as in a 'shadowgraph' machine used in industry for inspection, or the old GIA ProportionScope.
Here is a pic of what a scanner sees if viewing a profile according to the direction of the ideal index, when a main has been cut at a farther azimuth. This is the example of Fig.7, where one main was cut at 1° from ideal index (or azimuth), and therefore at a steeper slope (40.960°) to maintain the same join with the neighboring main on its left side.
In this case the scanner will see the left edges of the main, which show a bend in the profile (red) on the image plane - see enlarged view at lower left. The upper segment (join between mains) is still at 40.75° (recall that the new slope of the twisted facet was chosen to maintain this edge of the ideal cut), but this is not the slope of the main in question. The lower segment is at slope of 41.007°, which is also a false indication.
On the other hand, if the scanner looks only at the top and bottom end of the facet, and assumes a straight line between them, it would say 40.956° if it could measure that accurately, which would also be a false indication.
Only if the scanner looks at the actual 1°-shifted index, parallel to its trace (red line in girdle plane), will it see a straight profile and the true slope - by profile and/or tip-to-tip - of 40.960°.
Is this significant? That's for you to decide. I think that one decimal place is suitable for reports, in which case 40.960°, 40.956° and 41.007° would all round-off to 41.0°. The 40.75° indication would be unacceptable and the machine or user would have to ignore it.

Edit: I think this is what Paul was asking me for in May. It took this long to figure-out how to illustrate it - which I did thanks to the effort in this thread. Thanks, guys, for the stimulation; I gained by doing it.
A few minutes ago I hit a wrong key combination and found that I was typing Russian ! Perhaps that would make as much sense to many. Sorry for all the projection terminology. I was in the last class at my school to get this course, called 'Descripive Geometry', in 1950; it was discontinued because too many freshman engineers were quitting because of it. The administration realized that the purpose of a school is to make money.

 

[beryl]

Here is a blowup of the lower left enlargement.

 

[Rhino]

Hi Bruce,

Thanks for your response.

Rhino:
Yes, I am ''splitting frog hairs''. That is how I feel about ''errors'' which may occur in readings by machines such as Sarin, Ogi, etc. Don''t pursue this any further on my account.

No sweat. Hey ... I am perhaps the simplest kind of scientist you''ll ever meet. Test, observe, test again, observe. If I don''t see or note any changes, I make my conclusion and move on.

Recall that this thread was created only to clarify the difference between azimuth shift and ''yaw''; I think that has been done.

Absolutely. Heh... if even you have a problem fully understanding "yaw" as this is a private definition understood by only perhaps 2 people in the world ... believe me ... I would never pretent to fully know what''s in the heads of some. Who knows ... that definition may change in that person''s head and I''d be out of the loop completely & immediately. That''s why I''m focusing my studies on azimuth angles and their impact on the face up appearance/optical signature. That is an established metric whose definition can not change which can, as far as my observations are going so far can be accurately measured and observed.

Garry''s example shows another important point - the person using the machine must instruct it and interpret its information correctly.
Beware of instruments - they can be helpful or misleading. Use your eyes and common sense also. A diamond that looks good IS good. Data are useful only for remote evaluation or appraisal.

I would make one correction to your statement. Please correct me if I''m wrong but I would say ... "the person designing the machine must instruct it and him and the end user must interpret its information correctly. This person would be Sergey, Yuri and the team at MSU. From the dialogues I have had with the MSU team over the course of the years I know them (roughly 5 years now) and reading the materials that have been produced from their lab, the models I have perseonally received from both them and Garry, I have to tell you ... I am fully confident in their science.

If I have lead you to believe that I rely on numbers more than direct assessment Bruce I apologize for that. I never meant to convey that thought ... anywhere. Matter of fact if you can point out to me in my writing where I do such, let me know as I''d like to add a disclaimer or modify the statement. On the contrary Bruce I would place MUCH HEAVIER EMPHASIS on direct assessment. Mike Cowing and I have discussed this at length. Anyone who knows me or had dealt with me will tell you the same. When we give presentations in our store and I am introducing clients to the technologies we use in helping make our decisions I always ... always emphasize ... that the technologies mean nothing if they do not correllate to human eye observation. We take clients through 2 types of analysis. One which I call the "critical analysis" and immediatley after "the practical analysis" and how that technology correllates to human eye observation taking them into 4-5 different lightint conditions to observe the change in appearance in each and the correlations. My advice at the end is always ... get what pleases your eye most since you will be living with it for the rest of your lives. You''d be amazed the percentage of clients whose eyes 100% agree with the technologies.

Having said that Bruce I am interested in noting what numerical measurements, things that can be physically measured on the diamond, affect their optical signature. It is a personal study of mine which I believe will never end. I am, as a research gemologist driven by the same things that drive you perhaps ... What drives me? (heh... this is going to sound like its out of the Matrix) but I am driven by the question. Which question? The next one that needs an answer. At least in this Gman''s mind.

BTW: I did not recognize that ''.dmc'' meant a DiamCalc file; ''computerese'' frightens me. I have DiamCalc - a gift from Sergey; in fact, some of the features in it were my contributions. I also have H&A viewer - a gift from Brian. I have IdealScope - a gift from Garry, and its light source - a gift from Lieve Peeters and Paul Slegers. I have ASET - a gift from Peter Yantzer. Do you have ''Gemshape/Facet Designer'' by Anton Vasiliev? If not I will send it to you and demonstrate it when we get together - perhaps in the FoodCourt at the Casino of the Sky some Wednesday.

I would really appreciate that Bruce. Heh.. now I''m thinking of what kind of gift I can muster. I see Sir John has thought of one

... sorry John. I like Bruce but for the price of a Helium he''d have to grow some new body parts and lose certain others and I would have to be lied to about it too!

Too funny.

I just noticed your ad at the top of the page. ''Square Hearts & Arrows'' ! That interests me.

You''ll have to see these to believe em. I can send you a DiamCalc file on one if you like. Of course seeing it is preferred but they are the only squares we have found with optics akin to the finest rounds in way of contrast brilliance (brightness), fire and scintillation. I look forward to our meeting.

Kind regards,

 

[beryl]

Rhino:
I was referring to Garry solving the wrong problem with DiamCalc and applying the data to another problem.
I was editing the text (red) of Fig.8 while you were posting. You may want to read it.
As you suggest, the definition of 'yaw' may have changed along the way, so I now avoid the word.

 

[Garry H (Cut Nut)]

Date: 9/11/2005 12:31:50 PM
Author: Rhino

Date: 9/10/2005 8:55:41 PM
Author: Garry H (Cut Nut)

Date: 9/10/2005 8:11:48 PM
Author: Rhino
Heh... that''s cause Garry probably responded after having a little vino.

You''r on the money Rhino
it was late Friday night after our traditional Japanese dinner with friends

Do I know you Garry or what?

Hey ... I''m typing out a letter here on this laptop and was recalling what I think is perhaps the very first time we exchanged dialogue. Do you recall a thread about ''the bowtie of a marquise''? This is pre-pricescope and even pre-idealscope days. Everyone in the thread was accounting it to light leakage (LOL... if I recall RockDoc wasn''t even sure) and I stood alone in that thread trying to convey the phenomena i was seeing through the FireScope. I had deduced that it definitely was not leakage, but that those facets were functioning as reflectors (reflecting back the shadow of the eye). The reason this stands out in my mind is becuase, if I remember correctly, you were the only one who stood with me while the eggs were being thrown and I was being publicly ridiculed. Time and science has proven who was correct but since that day I had always felt a certain kinship with ya.

Just thinking out loud here but thought I''d share that. Do you remember that thread?

All the best,

Sure do Rhino.
In teaching the diamond course here down under 20 years ago I developed the sheet of paper with a small peep hole to make the bow tie go away. This proves to people that it is not leakage.
I too learned this from the Firescope

 

[Serg]

re: Only if the scanner looks at the actual 1°-shifted index, parallel to its trace (red line in girdle plane), will it see a straight profile and the true slope - by profile and/or tip-to-tip - of 40.960°.
Is this significant? That''s for you to decide. I think that one decimal place is suitable for reports, in which case 40.960°, 40.956° and 41.007° would all round-off to 41.0°. The 40.75° indication would be unacceptable and the machine or user would have to ignore it.

Wrong.
Bruce,
Helium algorithm is much more complex than simple idea had been described by you.

 

[Rhino]

Date: 9/12/2005 12:06:55 AM
Author: Serg
re: Only if the scanner looks at the actual 1°-shifted index, parallel to its trace (red line in girdle plane), will it see a straight profile and the true slope - by profile and/or tip-to-tip - of 40.960°.
Is this significant? That''s for you to decide. I think that one decimal place is suitable for reports, in which case 40.960°, 40.956° and 41.007° would all round-off to 41.0°. The 40.75° indication would be unacceptable and the machine or user would have to ignore it.

Wrong.
Bruce,
Helium algorithm is much more complex than simple idea had been described by you.

Hi Sergey.

Thank you for answering this. I think Bruce posted the identical thing in this thread too where I had responded. I was a little amazed that Bruce was making a comparison between the measuring capabilities of the old GIA silouhette screen and scanners... especially Helium. I''ve used both and I know there is a universe of a difference. Bruce is a gentleman so I don''t believe he was trying to imply that the Helium and the old GIA thing are on the same par but I don''t want to assume *anything* in Bruces mind. I''ll let him answer. Thanks for your input though Sergey. When I''m around you guys, you''re the teachers ... I''m the student.

Best regards,

 

[Rhino]

Date: 9/11/2005 1:35:00 PM
Author: beryl
As you suggest, the definition of ''yaw'' may have changed along the way, so I now avoid the word.

LOL... if we could just be mind readers...

We''d be on that beach right now man!

I thought I had grasped the concept in the old thread I was/may about to resurrect as I am interested in continuing the discussion on a more relaxed & intelligent note.

The concept you introduced in this thread added another factor that wasn''t in the other ... that of doubling the main. I see this has been a misunderstanding of your understanding of the subject so I guess neither of us should attempt to crawl into Brian''s brain.

I''ll finish reading through that again and finish my response. Excellent stuff though and am glad you are here to discuss.

 

[beryl]

style="WIDTH: 101.11%; HEIGHT: 276px">Date: 9/12/2005 1:16:12 AM
Author: Rhino

Date: 9/11/2005 1:35:00 PM
Author: beryl
As you suggest, the definition of ''yaw'' may have changed along the way, so I now avoid the word.

LOL... if we could just be mind readers...

We''d be on that beach right now man!

I thought I had grasped the concept in the old thread I was/may about to resurrect as I am interested in continuing the discussion on a more relaxed & intelligent note.

The concept you introduced in this thread added another factor that wasn''t in the other ... that of doubling the main. I see this has been a misunderstanding of your understanding of the subject so I guess neither of us should attempt to crawl into Brian''s brain.

I''ll finish reading through that again and finish my response. Excellent stuff though and am glad you are here to discuss.

In Fig.2 & 3, I was trying to illustrate the difference between azimuth shift and ''yaw'' - for your sake!
The half facet of Fig.2 was to show you what would happen if we had azuimuth shift only, without adjusting the slope as shown in Fig.3. It was not a misunderstanding.