How significant are the star facets and lower girdles info?

........... Karl has joined the diamond trade and is now posting as Karl_K

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Ira (Ruffles have Ridges) Z.
____________

If you're looking for diamond shopping tips...this (along with this update) might do the trick!

however...caution: known to have been regarded as armed and dangerous…

Wink Jones
GG
Winfield's/High Performance Diamonds

Ira,

Inaccurate data won’t tease out anything.  I’d be surprised if anyone was telling you that 3D scans reveal more than actual imagery.  Hardware calibration and built-in measurement errors skew data.  There are elements to a diamond such as facet yaw that are not picked up by Sarin/Ogi.  Software calculation error is also possible.

However you slice it a software simulation is only a prediction.

Natural viewers show things distinctly and you are observing the real end result, not a prediction.

Actual assessment remains the obvious, elegant answer.  It’s the same thing that guided Cardinal Mazarin, Henry Morse and Tolkowsky.  Tools have evolved now.  We have better scopes and new reflectors.  We’re even working towards mechanical assessment (Imagem, Brilliancescope & ISee), but I still trust a master with a loupe over a computer simulation any day of the week and twice on the Sabbath.

Ideal-scope/ASET and H&A Viewers have no error.  They are easily standardized for those wishing to do so.  I’d also say it’s more realistic to expect an ideal-scope or ASET image than to expect every dealer in the country to run out and buy a Sarin/Ogi.

I hope that clarifies, Ira.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Date: 8/4/2005 12:52:01 PM
Author: Midnight

John,

I guess I will continue to peep until WF add the LGF info to their Sarins. Do you anticipate WF will provide this info in the near future? I am not an expert on the Sarin/OGI scans but does every single scan that is processed automatically provides the LGF on the report? One Pricescope vendor mentioned that their OGI scan can't provide the LGF and that only the Sarin can. Thus, they had to 'manually' hand measured it when it was requested. I had the impression that the OGI had this capability.

(Hey Midnight, I hope you know ‘peeps’ meant ‘people’, not chickens!) 

Short answer

As GIAs cut estimator becomes popular Whiteflash may decide to add the LGF average on our pages.  Meanwhile we will continue to safeguard the consumer - just as we always have with this and many other issues of expertise.  Let’s not limit our discussion to minor facets:  It can be about expert analysis of durability relative to inclusions/cleavage planes, girdle treatments, patterning assessment, yaw assessment and other professional assessment a customer is hopefully paying for when he/she buys from a trusted authority.

Longer answer

(A) This information has always been important.
(B) We have always safeguarded these things for consumers. 
(C) Now consumers are aware of minor facets, but because measuring devices aren’t accurate they stand to get bad information.

Since you asked about Whiteflash and minor facets:  Brian Gavin’s minor facet philosophy has been available for a long time.  Specific relationships between lower girdle facets and pavilion mains have been fundamental to the PATTERNING soapbox we have been shouting from since the 90s.

The labs spent 100 million dollars to figure out that minors are crucial (GIA) and that actual observation of light dynamics (AGS ASET) is critical to assessment.  Meanwhile, cutters like Brian have known this for years.  “It’s all in the hearts”… (we have to stop him from wearing sandwich boards and ringing a bell about this).

What happens in the pavilion is of primary importance.  The way that lower girdles relate to mains is a key to acquiring the best Visual Balance™.  Minor facet relations were the foundation of Brian’s presentation at the International Diamond Cut Conference in Moscow more than a year ago.  The absence of yaw drives optimization of light return.  Yaw, something still not widely understood, can have more influence on appearance than minor facet configurations...  So where is the GIA input estimator for yaw??

“It’s all in the hearts.”  Repeat after me.  “It’s all in the hearts.”

I showed you the only three lower girdle constants GIA will be using (above), visible via ideal-scope.  I’ll post some examples of how you can determine lower girdle dynamics via hearts patterning to a much more discriminating level below.

Simply put, for our part anyway, we have a set of standards to safeguard people who buy our goods – and all of our diamonds fall within these standards.  Even Expert Selection goods are cut for these standards and perform similar to ACA because of it.  They may not meet our strict patterning specs of ACA, but that is why there is a difference in price.

Other vendors look out for customer interests as well - via analysis, pedigreed goods, experience and know-how, etc.  Obviously not all have the same methods, but I suggest that anyone ask a seller or an appraiser what things they do to ensure that their customers are served with a level of professional expertise.  The best will proudly tell you.

Whether the info is on a description page or not, cutters, sellers and appraisers with expertise and integrity will always look out for their clientele’s best interests.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

........... Karl has joined the diamond trade and is now posting as Karl_K

Wink,

Consumers will decide what level of info they desire individually.  ASET and a H&A viewer can be bought for about $200, or they can just consider that a part of the cost when they trust a vendor like you to perform the analysis.

Wink and others have been safeguarding consumers for years – even those who didn’t know major proportions (not to mention minors…rounded!).

And…For the consumers who like to read PS, acquire knowledge and give advice, I suggest you go buy an ASET and a H&A viewer and sit and sift through a few hundred diamonds, noting how useful these tools are, before you go buy that $20,000 Sarin DiaMension to give you less accurate data. 

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Ira (Ruffles have Ridges) Z.
____________

If you're looking for diamond shopping tips...this (along with this update) might do the trick!

however...caution: known to have been regarded as armed and dangerous…

........... Karl has joined the diamond trade and is now posting as Karl_K

Here is some info for those interested in a tutorial on assessment of minor facets from actual imagery.

Of course, with these examples we are talking about a high quality level of patterning.  We have always cut this type of diamond because it’s our personal taste.  If you don’t like orderly symmetry that’s fine, but we are into it.  We believe patterning optimizes light return thanks to focused alignment of the mirrors in the pavilion ("it's all in the hearts"). We also believe that specific minor facet relationships, along with symmetrical patterning, result in the best Visual Balance.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

So in the GIA metric, anything between 75% and 82% will be judged as if it were 80%...

Um.  Why can't 78% be 78% and 82% be 82%?  They are completely different looks.  The character of a well-patterned diamond alters significantly between these numbers.

Let’s look at 78%, 80% and 82% lower girdles as they would appear.  First the crown view.  You can see that the differences here are, logically, less obvious than the 75-80-85 above.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Now the pavilion view.  This is the view where Brian does his assessment of quality:  It’s  “all in the hearts.”

You can see where even the differences between 78%, 80% and 82% LGF are distinct:

78% - Robust hearts with slight separation from arrowheads above (pointing to the culet).
80% - Narrower hearts with notable separation from arrowheads.  Slight splits appear at the Vs.
82% - Narrow hearts with significant separation from arrowheads.  Notable splits at the Vs.

Can you tell the difference?  I sure can...  And the view through a H&A viewer is an actual image, not a simulation based on a 3D scan that has given inaccuracies or a cut estimation made with data rounded to 5%.  Fie! 

This is the method Kazumi Okuda and his contemporaries used to enable true patterning, and it's the method Brian used to design (and is still using to assess) ACA.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Rhino
Good Old Gold

Rhino
Good Old Gold

Wink Jones
GG
Winfield's/High Performance Diamonds

It's exciting that these recent threads have begun, since Brian introduced this information years ago and has been patiently waiting.

Rhino, you know I have great respect for your expertise, but I need to correct some of your comments regarding facet yaw.

Lightscope and H&A Viewers

I suspect only the crown of the diamond is surrounded by reflecting material in your lightscope, correct?  If this is so, a 3D view of distortions and angles of incidence is not possible in the pavilion.  Even if it's not so, the pavilion view is the only view that fully discloses yaw.  Do you have examples of what you are taking about?

I imagine it's possible to assess reduction of optimization (less robust and even light return) and some stray reflections DUE to yaw in lightscope.  This is also possible with ASET and Ideal-scope.

The full extent of yaw can only be assessed in a H&A viewer.  The hearts view of a diamond fully ensconced in the reflecting element shows distortions, angles of incidence and stray reflections, since it is an all-inclusive 3D view.  I'll attach images below.

Brilliancescope

Brilliancescope shows robustness of light return in its metric.  ASET and Ideal-scope/lightscope also do this.  BS does have photos and you can see symptoms of yaw in those, but you cannot actually see the extent of yaw, the distortions or the angles of incidence.

Jon, you may be interested to know that yaw can be responsible for some of your 'hot spots' on BS, so it's rewarding an undesirable diamond quality.   While on that topic, diamonds with LGF > 80% are also rewarded by BS, even though they are not as visually balanced through a range of lighting as those with LGF just under or at 80%

Sarin/Ogi

This is not correct.  Sarin and Ogi do not detect yaw.  Sarin measures angles.  OGI, because of patents, establishes points and then deducts angles.  In both cases the machines work from point to point seeing flat facets in 2D shadow of the diamond.  If the rotation of the machine table doesn't match the azimuth of the facet (as it does not with yaw - see diagram below) the slope indications are incorrect.

Edited to add:  Extreme yaw shows itself as azimuth shift and is measured by Sarin/Ogi and represented in a 3D model.  Jon, maybe that is what you're seeing?

Helium

Brian was one of the only Americans at the IDCC in Moscow, and had the privilege of an introduction to Helium's fundamentals.  Very impressive!  Garry has also described the system to me and it uses different axes than Sarin/Ogi.  We are hopeful it measures yaw and waiting for evidence.  Jon, any info you can add would be welcome.


Also, Jon, before you complete your web page about this you may want to consult with Brian, who is the identifier of yaw.  We have dedicated considerable research along with Bruce Harding who, self-admittedly, had his CAD skills pushed to the max on this project.  Peer review is always a good thing, friend.

Lest any think I am Rhino-hunting, I'm not (and besides, he has thick skin)   I want to be clear that I think highly of Jonathan and his enthusiasm for all aspects of dia-knowledge.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

For anyone we haven’t yet lost… (I’ll do a tap-dance if AGBF is still reading)

Here is a diagram explaining the yaw phenomenon.  It happens either by sloppy cutting, or when a cutter cannot polish a facet in the conventional manner (girdle to culet or culet to girdle) and must adjust the ‘cheater’ screw to take that facet from ‘east to west.’  Brian Gavin identified facet yaw years ago.  In the last year Brian, Paul Slegers, Bruce Harding, Garry and I have had many exchanges about its cause and effect.  Bruce is a master of AutoCAD and has designed gem software.  I diagramed yaw for Brian in a rudimentary way and Bruce made art out of my scribblings.  In addition to being a foremost diamond authority, Bruce is also a prince of a guy - one of the truly wonderful people in this trade.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

That diagram is just one choice for yaw.  There are many combinations.  In the above illustration the height of the meets are 50%.  Tips of scallops at usual azimuths.  The main is yawed 4.82 degrees, and the half on the right is only 6.21 degrees from its correct main index, so the azimuth angle between them is only 1.39 degrees.  You can see this in the similar direction of the shading lines, parallel to the girdle plane.  The two reflections would be almost simultaneous in the diamond.  If you rotate both halves counterclockwise, the far left one would have gotten wider and far right narrower unless you shifted its azimuth too and that would look more distored. 

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

This was one of my rudimentary drawings when I was first trying to grasp the EFFECT of yaw - not the cause or the 3-dimensional realities, which Bruce rendered.

This is very simplistic as I was only working in 2D, but the concept of how reflections can occur at different angles of incidence than intended is plain here.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Here is a diamond with some yaw and lower girdle facets >80%

The pavilion (hearts) view displays moderate yaw in almost every pattern and lower girdle facets well over 80%. 
The arrows (crown) view displays some of the effects of yaw in the same diamond (under the table), but as you can see the hearts view is significantly more telling about the cut.

(Jon - this is why I'm curious about your lightscope statement)

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

Next are some examples of yaw within patterned diamonds:

I want to be clear that the definition of “POOR” pavilion patterning refers to these diamonds compared to Brian Gavin's standards of true patterning.

These are diamonds that are patterned better than average makes.  Elements of yaw appear in the H&A viewer, though they are not visible in crown views.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

These near-true examples show elements of yaw (orange), lower girdles > 80% (green) and lower girdles on the bottom right example < 75%.

A 3D scan done by Sarin/Ogi could pick up the lower girdle data – some error possible - but would not pick up all yaw.

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

John

__________________________

John Pollard

Whiteflash Director of Education 2004-2007

........... Karl has joined the diamond trade and is now posting as Karl_K