GIA''s amazing new patent

[He Scores]

.


Sniper called me and we discussed defining various terms.

Sniper''s never called me crazy. That''s what I like about him.

It''s nice to talk to someone who can grasp the difference between the theoretical paper talk to the actual 3D manipulation of this thing call diamond.


Bill Bray
Diamond Cutter

 

[adamasgem]

Date: 1/29/2007 12:08:08 PM
Author: Serg

Date: 1/29/2007 11:36:33 AM
Author: adamasgem

Date: 1/29/2007 7:29:09 AM
Author: Serg

Date: 1/28/2007 3:07:33 PM
Author: adamasgem
Here is an example of phasing up girdle profiles, for identification purposes (sorry GIA, you can''t patent it, it is public domain now), or establishing a zero azimuth position for run to run consistency checks... identifying like facets for run to run statistics, or calibration use..

It is a statistically powerfull tool for identification. These were done with 40 slice RSL girdle profiles..

Any comments Serg on the validity of the approach?

Marty, We use combination rules for establishing a zero azimuth position.
ANY one rule is not enough usually for round diamond with perfect symmetry

Serg.. My example showed the applicability of picking one stone from similar stones done on the same scanner.. What I am suggesting is that the technique may be applicable for finding the SAME zero azimuth position on a single calibration stone.. the initial calibration done on a different scanner..

Obviously, additional ''rules'' can help

The issue is a robust algorith to enable comparison of the same facets on a run to run basis, that is why I suggested a calibration stone with a LARGE flat girdle facet as an additional reference point..

Marty,
If you scan one diamonds on different Helium scanners you will receive same looks reports( same zero azimuth reference)

Accuracy for girdle facets can not be good enough for reference azimuth

Serg. You are saying that the X,Y,Z mesh will automatically align and the 0''th facet (Main for example) will always be the same, no matter what Helium scanner you use... That is interesting and very usefull in itself.

I don''t believe that to be the case for Sarin, I''ll have to check..

It certainly wasn''t the case with the original Sarin RSL files which defined a 40 slice girdle profile whose phasing was all over the place, not that it was necessary at the time.

I wouldn''t downgrade the Helium''s capability for consistency in girdle profiles sufficient to establish a unit to unit azimuth reference, as there are many more facets for a correlation analysis like I performed. The phasing should be improved, by my way of thinking...

If you have already done the job in your software, then you could provide a "reference faceted girdle CZ" to your users for use in calibration and/or sanity checking, I believe, with automatic run to run statistics on each facet as a statistical process control. It would establish finer information on standard deviations on the facet angle measurements.

Johnathon, could you send me a dozen or so STL files from Helium scans on the same stone, done by replacing the stone on the pedestal each time? I''d like to take a look at that..

 

[Garry H (Cut Nut)]

Date: 1/29/2007 1:37:49 PM
Author: adamasgem


If you have already done the job in your software, then you could provide a ''reference faceted girdle CZ'' to your users for use in calibration and/or sanity checking, I believe, with automatic run to run statistics on each facet as a statistical process control. It would establish finer information on standard deviations on the facet angle measurements.

Marty CZ does not have flat facets

 

[diagem]

Date: 1/29/2007 1:18:31 PM
Author: He Scores
.


Sniper called me and we discussed defining various terms.

Sniper''s never called me crazy. That''s what I like about him.

It''s nice to talk to someone who can grasp the difference between the theoretical paper talk to the actual 3D manipulation of this thing call diamond.

Bill Bray
Diamond Cutter

Yes, its called open-minded......, nicely said.

 

[adamasgem]

Date: 1/29/2007 2:12:23 PM
Author: Garry H (Cut Nut)

Date: 1/29/2007 1:37:49 PM
Author: adamasgem


If you have already done the job in your software, then you could provide a 'reference faceted girdle CZ' to your users for use in calibration and/or sanity checking, I believe, with automatic run to run statistics on each facet as a statistical process control. It would establish finer information on standard deviations on the facet angle measurements.

Marty CZ does not have flat facets

Do you mean the facet junctions or the facets faces themselves..
Of course it also depends on what is used to cut and polish them, wouldn't it?
You could also use a harder material like white sapphire..

You are implying, correctly or otherwise, that scans of colored stones are much less reliable than scans of diamonds..
I'll agree that the facet junctions are less reliable due to tendency of rounding..

 

[adamasgem]

Date: 1/29/2007 2:23:53 PM
Author: DiaGem

Date: 1/29/2007 1:18:31 PM
Author: He Scores
.


Sniper called me and we discussed defining various terms.

Sniper''s never called me crazy. That''s what I like about him.

It''s nice to talk to someone who can grasp the difference between the theoretical paper talk to the actual 3D manipulation of this thing call diamond.

Bill Bray
Diamond Cutter

Yes, its called open-minded......, nicely said.

Thanks guys..

 

[Garry H (Cut Nut)]

Date: 1/29/2007 4:44:09 PM
Author: adamasgem

Date: 1/29/2007 2:12:23 PM
Author: Garry H (Cut Nut)

Date: 1/29/2007 1:37:49 PM
Author: adamasgem


If you have already done the job in your software, then you could provide a ''reference faceted girdle CZ'' to your users for use in calibration and/or sanity checking, I believe, with automatic run to run statistics on each facet as a statistical process control. It would establish finer information on standard deviations on the facet angle measurements.

Marty CZ does not have flat facets

Do you mean the facet junctions or the facets faces themselves..
Of course it also depends on what is used to cut and polish them, wouldn''t it?
You could also use a harder material like white sapphire..

You are implying, correctly or otherwise, that scans of colored stones are much less reliable than scans of diamonds..
I''ll agree that the facet junctions are less reliable due to tendency of rounding..

Correct - they are not flat.
Take best and worst quality CZ and look at the refletions of a ceiling light or distant objet with your naked eye (with specs if you need them).

You will see the facets are never flat.

What you should see is something like this - i just took this photo - I am focused on the ceiling - not the table of the stone.

As you move this type of reflection across he stone you will see the CS''s are never flat - whereas any diamond as long as it does not have a grain line or knat running across it will be a perfect mirror.

 

[aljdewey]

...

 

[adamasgem]

Date: 1/29/2007 6:19:44 PM
Author: Garry H (Cut Nut)

Correct - they are not flat.
Take best and worst quality CZ and look at the refletions of a ceiling light or distant objet with your naked eye (with specs if you need them).

You will see the facets are never flat.

What you should see is something like this - i just took this photo - I am focused on the ceiling - not the table of the stone.

As you move this type of reflection across he stone you will see the CS''s are never flat - whereas any diamond as long as it does not have a grain line or knat running across it will be a perfect mirror.

I don''t know what your pictures show, but what you see as a reflection on the facet surface will have to do with BOTH flatness and quality of the polish...

Certainly colored stones that get Spectrum awards can''t compare to machine cut, mass produced CZ''s in either flatness or polish nor facet junctions...

 

[RockDoc]

Sarin''s Tech Support had me use three different size CZ''s to use as "calibration masters".

I think the "object" is to see that the scans are relatively the same each time they are scanned.

Rounded facet junctions might be an issue, but as long as the scans are the same, is having diamonds instead of CZ that critical. Don''t think Sarin would mislead their customers, would they?

Rockdoc

 

[adamasgem]

Date: 1/29/2007 11:06:09 PM
Author: RockDoc

Sarin''s Tech Support had me use three different size CZ''s to use as ''calibration masters''.

I think the ''object'' is to see that the scans are relatively the same each time they are scanned.

Rounded facet junctions might be an issue, but as long as the scans are the same, is having diamonds instead of CZ that critical. Don''t think Sarin would mislead their customers, would they?

Rockdoc

Bill Run a CZ three times moving the stone between each run and send me the SRN files please..

 

[Garry H (Cut Nut)]

Marty and Roc, the issue is that doing comparisons with CZ''s on a single type of scanner like a Sarin with the same lens set up might work for testing - but since the points measured and processes in different scanners are different, the curved facets on CZ will not work for the level of accuraccy required for comparison purposes.

The rounding of facet edges is not the issue as much as the curving which you can see in the very best CZ''s that I have ever seen - including the top end Thai company that wink uses and Signity / Swarovski CZ.

The photo is to show that you do this test by looking at the distant reflection with a straight edge - like the edge of a fluoro tube - or a partly open venetian blind.

 

[strmrdr]

Garry is the rounding a function of how cz''s are cut or is it a limitation of the material itself?
ie. can flat facet cz''s be cut?

 

[Garry H (Cut Nut)]

Date: 1/29/2007 11:42:08 PM
Author: strmrdr
Garry is the rounding a function of how cz''s are cut or is it a limitation of the material itself?
ie. can flat facet cz''s be cut?

Dont know the answer Storm?

But i do know that because of the compast bonding in diamond that it takes astronomically better polish than other materials - and often i have noticed that I can read the writting on a light globe across the room when by chance it comes into focus on the table.
I do not remeber having that experiance with colored gems - but why dont we all try it?

 

[Serg]

Usually CZ has 3 and more microns roundness for 1 mm facet.
OctoNus use only diamonds for calibration Helium( Usually We send one diamond with each HP scanner for checking calibration after transportation or calibrate client diamond by our master diamond)

 

[He Scores]

I think the main reason for any rounding of a CZ facet is the fact that diamond is nature''s hardest substance and can be polished to a mirror finish UNLIKE any other gems. CZ isn''t as hard. When the hardness scale is consider a ten to a nine is like a CAT 10 Hurricane to a CAT 5. It''s alot more! Nothing comes close to the actual hardness of diamond. They come close on a scale of hardness but that''s yet another shortcoming of a rubric style of grading system, but I digress.

Other reasons that may account for a "rounding of the edges" are, the amount of the abrasion mixture used by the lapidary could be a factor as also is the hardness of the actual lap they grind the facet on.

As far as using a CZ as any type of comparision stone either for calibrating a measuring device or using a CZ master color comparison set, I don''t think it''s the top notch thing to do if you want solid results.


Bill Bray
Diamond Cutter

 

[Rhino]

Date: 1/27/2007 8:37:05 PM
Author: Garry H (Cut Nut)

Date: 1/27/2007 4:33:07 PM
Author: Rhino

Here''s a question for ya Serg. If the Helium is using the table plane as its reference and the table is tilted will this skew the results of the Helium scan causing it to give faulty measurements?

Rhino I think the answer is that since the stage and there fore the table is the reference plane - then the stone will have every other plane of symmetry tilted, but the table would be shown to be at ground ''zero''.

Remeber the stone I found that showed H&A''s yet GIA gave it only Good symmetry. You must have read this before - if you have not then please do now.

http://www.gemology.ru/cut/english/symmetry/6.htm

And hence the development of the crown and pavilion angle symmetry and variation at the bottom of helium reports titled ''OctoNus Theory'' that Sergey and Yuri developed as a result of this stone that I found and we wrote about in the above article.

Hi Garry,

I''ll check this out. I''ve always noted the "Octonus Theory" on the Helium reports but never quite understood why they were there as they always seemed to corellate to the other data on the report. I''ll read through this and let ya know what I think.

Peace,

 

[Rhino]

Date: 1/28/2007 3:23:37 AM
Author: adamasgem
If someone wants to check the angular accuracy of their scanner, look at right angle prisms from edmund

http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2329&search=1

the 5mm prism 5MM HT RA FS PRISM @ $80 has an angular spec of +/- 40 arc seconds or 0.0011 degree angular accuracy


Unfortunately 0.4 inch by 0.4 inch guage block ar probably about 1 inch long (25.4mm) , and they are not specificed for length accuracy, but cutting one in half will still give you two surfaces with specs of less than 0.000005 inches or 0.000127mm and the length random, the length could be lapped after cutting

see http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2221210&PMT4NO=17209966

They would have to be cut, I can cut them and debur the edge for anyone who wants to try the experiment but I dont have the equipmet to guarantee parallism on the length.. but one width and the height would be within 0.000004 inches..
They are 31.12 each. If you have a Sarin that can handle the 23.4 inch length then you wouldn''t have to cut them..

Johnathon, does your Sarin handle a rectangle 25.4mm long ?

I have the Sarin with the 3 interchangeable lens. I can''t recall the exact tolerances of the widest angle lens but its been a while since I tried scanning anything that large.

 

[Rhino]

Date: 1/28/2007 2:13:53 PM
Author: He Scores


Rhino.

Since during the cutting process all the facets etc. are measured in relationship to the table I think it''s appropriate that any measuring device does the same.

If the table is skewed, it skews up (sic) all the rest of the measurements.

Rightly so, since a skewed table is cutting error.

Bill Bray
Diamond Cutter

Makes sense Bill.

 

[Garry H (Cut Nut)]

Date: 1/30/2007 11:07:05 AM
Author: Rhino

Date: 1/27/2007 8:37:05 PM
Author: Garry H (Cut Nut)

Date: 1/27/2007 4:33:07 PM
Author: Rhino

Here''s a question for ya Serg. If the Helium is using the table plane as its reference and the table is tilted will this skew the results of the Helium scan causing it to give faulty measurements?

Rhino I think the answer is that since the stage and there fore the table is the reference plane - then the stone will have every other plane of symmetry tilted, but the table would be shown to be at ground ''zero''.

Remeber the stone I found that showed H&A''s yet GIA gave it only Good symmetry. You must have read this before - if you have not then please do now.

http://www.gemology.ru/cut/english/symmetry/6.htm

And hence the development of the crown and pavilion angle symmetry and variation at the bottom of helium reports titled ''OctoNus Theory'' that Sergey and Yuri developed as a result of this stone that I found and we wrote about in the above article.

Hi Garry,

I''ll check this out. I''ve always noted the ''Octonus Theory'' on the Helium reports but never quite understood why they were there as they always seemed to corellate to the other data on the report. I''ll read through this and let ya know what I think.

Peace,

Rhino you have been involved in countless discussions about this issue and i must have refferred to that article 100 times over 3 years. You have not read it yet - so make sure you do now please.

Then you will understand Octonus Theory and why basing diamond cut quality results on measurements using the table as a reference point only makes sense to Bill, and makes no sense to people who care about the diamonds visual appearance.

I am sad that so many of the features listed on diamond grading reports are based on the reproducability of detection of the feature by a human with a micoscope or some mindeless instrument.

There is another discussion running here https://www.pricescope.com/community/threads/a-rising-tide-shrinks-the-jewel-business.56901/ about structural flaws in our industry. One such issue I believe is that labs provide a lot of information that may be of interest to gemologists and total nerds, but they use coded language to say this is a good diamond, this one is not so good and this one is shocking.


So why would GIA grade this diamond as only Good symmmetry when all the facet meet points closed?

 

[adamasgem]

Date: 1/30/2007 5:34:33 PM
Author: Garry H (Cut Nut)


So why would GIA grade this diamond as only Good symmmetry when all the facet meet points closed?

Let me guess:
1) They measured it with an OGI
2) FarceWare(TM) rounding
3) Someone had a hangover
4) Wrong submitter
5) All of the above

couldn't resist even though I realized later that it was the stone in the Octonus report with the table not parallel to the girdle plane

 

[Garry H (Cut Nut)]

fixed by Marty

 

[adamasgem]

'

Date: 1/30/2007 5:49:44 PM
Author: Garry H (Cut Nut)
Naughty Marty - you better read the article too Marty

I did after I wrote the post, that is why I just added a PS

But if it has a tilted table, I can't say I disagree with a "good"

 

[He Scores]

RE: Marty said: But if it has a tilted table, I can''t say I disagree with a "good"

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


I''m glad Marty and some others can see the severity of a tipped table. It has to be one of the most worst cutting errors if done unintentionally at the end of the stone (often times to refine the polish on the table or to enlarge the table). Tipping the table can litterally un-do all the precision of all the previous work.

I''m sure that most precision cutters would rather not have to touch it after the stone is finished.

Even if the cutter hits the table facet "flat on", the stone can grab from one direction of an influencing grain as it''s on the wheel resulting in the tip.


Bill

 

[Serg]

Date: 1/30/2007 5:59:58 PM
Author: adamasgem
'

Date: 1/30/2007 5:49:44 PM
Author: Garry H (Cut Nut)
Naughty Marty - you better read the article too Marty

I did after I wrote the post, that is why I just added a PS

But if it has a tilted table, I can't say I disagree with a 'good'

GIA G had been receive by rule about variation Pavilion angles. But variation Pavilion angle is absents. Diamond has table tilt only.
What should be rule for grade tilt table ?
I am disagree with GIA symmetry grade G for such diamonds. I think VG is Much more reasonable in such case.

Labs grade what they see or can measure. But usually it is too for industry tasks and consumers market too. Real tasks are more complex

 

[adamasgem]

Date: 1/31/2007 12:47:17 AM
Author: Serg

Date: 1/30/2007 5:59:58 PM
Author: adamasgem
''

Date: 1/30/2007 5:49:44 PM
Author: Garry H (Cut Nut)
Naughty Marty - you better read the article too Marty

I did after I wrote the post, that is why I just added a PS

But if it has a tilted table, I can''t say I disagree with a ''good''

GIA G had been receive by rule about variation Pavilion angle. But variation Pavilion angle is absent. Diamond has table tilt only.
What should be rule for grade tilt table ?
I am disagree with GIA symmetry grade G for such diamonds. I think VG is Much more reasonable in such case.

Labs grade what they see or can measure. But usually it is too for industry tasks and consumers market too. Real tasks are more complex

Serg... This is the issue of how to define the girdle plane..
An obvious tilted table is what I would call a commercial to promotional make, and deserves no better than a good.

The problem is in how to define the girdle plane and its relationship to the table.

All facet angle should be defined with repsect to the table, as that is the best reference and unambiguous (normally).

I''m looking at a best estimate optimal Kalman filter solution to the girdle plane based on the girdle facet centroids.. One can also use the girdle facet junctions, but the plane equation solutions get kind of bouncing around and may not converge as niceely.. I''l modify my software and maake the sample runs with any STN or STL file you wish to provide ...

 

[Garry H (Cut Nut)]

Date: 1/31/2007 1:02:34 AM
Author: adamasgem

Date: 1/31/2007 12:47:17 AM
Author: Serg

Date: 1/30/2007 5:59:58 PM
Author: adamasgem
''

Date: 1/30/2007 5:49:44 PM
Author: Garry H (Cut Nut)
Naughty Marty - you better read the article too Marty

I did after I wrote the post, that is why I just added a PS

But if it has a tilted table, I can''t say I disagree with a ''good''

GIA G had been receive by rule about variation Pavilion angle. But variation Pavilion angle is absent. Diamond has table tilt only.
What should be rule for grade tilt table ?
I am disagree with GIA symmetry grade G for such diamonds. I think VG is Much more reasonable in such case.

Labs grade what they see or can measure. But usually it is too for industry tasks and consumers market too. Real tasks are more complex

Serg... This is the issue of how to define the girdle plane..
An obvious tilted table is what I would call a commercial to promotional make, and deserves no better than a good.

The problem is in how to define the girdle plane and its relationship to the table.

All facet angle should be defined with repsect to the table, as that is the best reference and unambiguous (normally).

I''m looking at a best estimate optimal Kalman filter solution to the girdle plane based on the girdle facet centroids.. One can also use the girdle facet junctions, but the plane equation solutions get kind of bouncing around and may not converge as niceely.. I''l modify my software and maake the sample runs with any STN or STL file you wish to provide ...

Marty let me tell the story of this stone:

1. an Israeli dealer offered it, with a gIA report.
2. we look at the stones thru ideal-scope and it passed.
3. I saw the report 9I usually never bother reading them because we often do not use them in the sales process - most clients trust us and the first they see of it is when they get their approisal.
I noticed it was only GIA Good symmetry.
I also checked and say the H&A''s sym.
4. I scanned the stone and found out why?
5. When I knew the answer - I took it back to the dealer and 2 staff with Diploma''s of Diamond Technolgy, one also an appraiser, and asked them to tell me what was wrong with the symmetry with loupes only. None could find anything.
6. Only after being told that there was an off centered culet did anyone say they could see it - and believe me - it was damm hard to see - and could well have been imagination.
7. I sent the data to Sergey and Yuri - and Sergey developed "OctoNus Theory" as described in the article (he may have already developed the idea???? but this was when I became aware of it.)

There is no way such a magnificent gem can be downgraded from Excellent to Good.

 

[Garry H (Cut Nut)]

Here is its Sarin scanned .gem model.

There is a lower girdle facet error in the scan - the LG''s were longer than as represented - at the time there was a glitch - something i think to do with naming of lgf length and LGF depth.

The original scan date is sept 2002.

 

[diagem]

Date: 1/30/2007 9:37:30 PM
Author: He Scores

RE: Marty said: But if it has a tilted table, I can''t say I disagree with a ''good''

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


I''m glad Marty and some others can see the severity of a tipped table. It has to be one of the most worst cutting errors if done unintentionally at the end of the stone (often times to refine the polish on the table or to enlarge the table). Tipping the table can litterally un-do all the precision of all the previous work. On larger stones, ALL tables go through what is called "final polishing" of the table..., since the stone is usually based on the table against the (metal) dop for the brillianteering of the pavilion or the metal nails of the dop hold the table/stone in place for the brillianteering of the crown. scratches (among other things) are inevitable!!! the table must be polished at the end of the cutting/polishing procedure.

I''m sure that most precision cutters would rather not have to touch it after the stone is finished. very true, but not realistic.

Even if the cutter hits the table facet ''flat on'', the stone can grab from one direction of an influencing grain as it''s on the wheel resulting in the tip.
I believe that in most cases, even if you hit the table flat on the wheel, you will still get a fraction of a tilt. And yes i agree with Bill that influencing grain direction will result in some kind of minimal tilt.


Bill

And another factor worth mentioning, the girdle facets cut onto the stone are based on a 90 degree angle from the table.

 

[He Scores]

We should refer this "final table polishing" question to Brian at Whiteflash.

I polish the table early in the cutting stages to end up with more accurate mains etc. Of course, I''m not really sucessful at getting excellent finishes from GIA, not because of the table so much but of the type of wheel I use. To me, an accurately symetrical stone if far more important to my customers than one that may have an eensy weensy table mark. But, that''s just me. I take precautions not to scratch the table. Sectionalized cutters may not, especially if there''s another schlepper willing to fix up his mistakes. I don''t have that luxury since I make the entire stone.

As far as the girdle being 90 degrees, if you facet a girdle exactly that way you will see sort of a halo around the stone which is actually seeing a portion of the girdle. Most girdles are tilted slightly from the culet side to prevent this and for ease of cutting.

Bill