a cut question. to garry h and others

[WorkingHardforSmallRewards]

Date: 10/15/2007 1:36:02 AM
Author: Garry H (Cut Nut)
WH4SR there have been links off to technical discussions about this. They are a bit boring though.

Simply:


1. dust under the table on the scanner table - so deviations in the crown and the pavilion will match in a perfectly symmetrical stone. The deviations will be exactly 2X the tilt induced in the table by the dust.



2. dust or dirt under the table in the polishing dop



3. slippage in the dop during polishing


In the last 2 cases there is no basis for the deviation in the crown to match the deviation in the pavilion. That is why I could suspect that Storm was wrong in his initial recomendation.

but he coudl just as easily have been right yes?

or it could have just as easily have been table tilt?

 

[WorkingHardforSmallRewards]

well I was going to wait for your answer, but I am going to go to sleep so I will say it now. As I was reading this I couldn't help but think that in the end there simply isn't enough data. the scanners being used accompanied with certain other variables is causing for what seems to be a bit of a margin of error.

and if you know anything about the best by the name of "margin of error" trying to determine anything within that margin is really rather pointless is it not?

so it looks to me in my terribly uninformed state that using these numbers to evaluate "tightness" within certain margins (such as those in this example) is pointless and that perhaps these numbers should not be use as a selection tool amongst "tight" and "super tight" cuts but rather as a...well....

"weeding tool"

....

amongst particularly "loose" cuts and "tight" cuts.

 

[Garry H (Cut Nut)]

Date: 10/15/2007 1:50:18 AM
Author: WorkingHardforSmallRewards
well I was going to wait for your answer, but I am going to go to sleep so I will say it now. As I was reading this I couldn''t help but think that in the end there simply isn''t enough data. the scanners being used accompanied with certain other variables is causing for what seems to be a bit of a margin of error.

and if you know anything about the best by the name of ''margin of error'' trying to determine anything within that margin is really rather pointless is it not?

so it looks to me in my terribly uninformed state that using these numbers to evaluate ''tightness'' within certain margins (such as those in this example) is pointless and that perhaps these numbers should not be use as a selection tool amongst ''tight'' and ''super tight'' cuts but rather as a...well....

''weeding tool''

....

amongst particularly ''loose'' cuts and ''tight'' cuts.

Quite the contrary WH4SR''s. This information shows usage of tightness numbers is very difficult and misleading.

An ideal-scope for a round diamond and an ASET for a fancy shape provides a wealth of information for selection purposes. This will also pick up things happening in non reported minor facets.

The degree of anal analysis that storm was appplying at the start of this thread is a good example of disappearing into ever smaller and smaller circles of information overload.

If an IS image is good, but is insufficient for your mind clean symmetry needs then find a stone that also has great hearts and arrows as well.

Make sure there are no girdle or other cut issues etc and you have a great diamond.
Of course this and more can be done with Gem adviser too

 

[stebbo]

Date: 10/15/2007 1:36:02 AM
Author: Garry H (Cut Nut)
...

1. dust under the table on the scanner table - so deviations in the crown and the pavilion will match in a perfectly symmetrical stone. The deviations will be exactly 2X the tilt induced in the table by the dust.

I'm sure you meant the deviations will be an additional 2X the tilt.

Also 2X is a maximum and will only be achieved if the min and max facets were opposites and the tilt was exactly in their direction.

 

[Garry H (Cut Nut)]

Date: 10/15/2007 3:02:07 AM
Author: stebbo

Date: 10/15/2007 1:36:02 AM
Author: Garry H (Cut Nut)
...

1. dust under the table on the scanner table - so deviations in the crown and the pavilion will match in a perfectly symmetrical stone. The deviations will be exactly 2X the tilt induced in the table by the dust.

I''m sure you meant the deviations will be an additional 2X the tilt.

Also 2X is a maximum and will only be achieved if the min and max facets were opposites and the tilt was exactly in their direction.

Sorry Stebbo - you said you had read the article.
What I wrote is correct.

it slowly

 

[stebbo]

Date: 10/15/2007 2:38:22 AM
Author: Garry H (Cut Nut)

Date: 10/15/2007 1:50:18 AM
Author: WorkingHardforSmallRewards
well I was going to wait for your answer, but I am going to go to sleep so I will say it now. As I was reading this I couldn''t help but think that in the end there simply isn''t enough data. the scanners being used accompanied with certain other variables is causing for what seems to be a bit of a margin of error.

and if you know anything about the best by the name of ''margin of error'' trying to determine anything within that margin is really rather pointless is it not?

so it looks to me in my terribly uninformed state that using these numbers to evaluate ''tightness'' within certain margins (such as those in this example) is pointless and that perhaps these numbers should not be use as a selection tool amongst ''tight'' and ''super tight'' cuts but rather as a...well....

''weeding tool''

....

amongst particularly ''loose'' cuts and ''tight'' cuts.

Quite the contrary WH4SR''s. This information shows usage of tightness numbers is very difficult and misleading.

An ideal-scope for a round diamond and an ASET for a fancy shape provides a wealth of information for selection purposes. This will also pick up things happening in non reported minor facets.

The degree of anal analysis that storm was appplying at the start of this thread is a good example of disappearing into ever smaller and smaller circles of information overload.

Agree here - I''m sure 8* don''t give a damn about what Sarin says, otherwise as you said before, just shop on Brayscore.
I''d love to know how non-geometrically perfect an 8* isn''t if you ever did scans Jon (oh, and you''re allowed to say).

 

[stebbo]

Date: 10/15/2007 3:17:27 AM
Author: Garry H (Cut Nut)

Date: 10/15/2007 3:02:07 AM
Author: stebbo

Date: 10/15/2007 1:36:02 AM
Author: Garry H (Cut Nut)
...

1. dust under the table on the scanner table - so deviations in the crown and the pavilion will match in a perfectly symmetrical stone. The deviations will be exactly 2X the tilt induced in the table by the dust.

I'm sure you meant the deviations will be an additional 2X the tilt.

Also 2X is a maximum and will only be achieved if the min and max facets were opposites and the tilt was exactly in their direction.

Sorry Stebbo - you said you had read the article.
What I wrote is correct.

it slowly

Garry, your standing makes this relative whipper-snapper always pause in questioning you, but that article:

1. Looks at the worst case by making the min and max facet opposite.
2. Looks at the worst case by assuming the tilt is exactly in the direction of the min & max facets.

Hence I say 'maximum'.

But even in that worst case scenario, the article shows a table tilt of 0.8 degrees - your statement above declares that the deviations are exactly 2X - I can't see 1.6 degrees anywhere. I can see an additional 1.6 degrees though making 0.2 degrees (41.6/41. appear as 1.8 degrees (40.8/42.6).

I say 'additional'.

Shall I read it slower again?

Surely you didn't mean 'deviation' as in 'change in deviation'.

 

[stebbo]

Date: 10/15/2007 3:24:55 AM
Author: stebbo

I''d love to know how non-geometrically perfect an 8* isn''t if you ever did scans Jon (oh, and you''re allowed to say).

oops, double negative here. Drop one of them.

 

[Garry H (Cut Nut)]

Stebbo that stone is probably not perfectly symmetrical - just close.

1. dust under the table on the scanner table - so deviations in the crown and the pavilion will match in a perfectly symmetrical stone.

That is - you rest the stone on a bit of dirt and the table tilts by 1 degree.
As you scan the stone it wobbles at the culet, so the scanner says the culet is off center.

One side crown angle is 1 degree steeper, the other is 1 degree shalower = 2 degrees of variation.

Same with the pavilion.


The deviations will be exactly 2X the tilt induced in the table by the dust.

 

[Garry H (Cut Nut)]

Date: 10/15/2007 4:04:49 AM
Author: stebbo

Garry, your standing makes this relative whipper-snapper always pause in questioning you, but that article:

1. Looks at the worst case by making the min and max facet opposite.
2. Looks at the worst case by assuming the tilt is exactly in the direction of the min & max facets.

Hence I say ''maximum''.

I am talking about a perfectly symmetrical diamond Stebbo.
So yes - the deviation in the top lines up with the deviation in the bottom.
But Storm would still say "do not buy it" because it has a deviation. But it does not have a deviation.


I look at many scans of stones in DiamCalc, and I check them for deviations and they are common - and they almost always line up - the shallow side is over the steep side. Often these stones are H&A''s, but the vendors do not know it because their scan data tells them the stone has lessor symmetry. The stones are fine, the scan is lousy.

 

[stebbo]

Date: 10/15/2007 4:20:40 AM
Author: Garry H (Cut Nut)
Stebbo that stone is probably not perfectly symmetrical - just close.

1. dust under the table on the scanner table - so deviations in the crown and the pavilion will match in a perfectly symmetrical stone.

That is - you rest the stone on a bit of dirt and the table tilts by 1 degree.
As you scan the stone it wobbles at the culet, so the scanner says the culet is off center.

One side crown angle is 1 degree steeper, the other is 1 degree shalower = 2 degrees of variation.

Same with the pavilion.


The deviations will be exactly 2X the tilt induced in the table by the dust.

I was taking it a bit further than that simplification: real stone, real scanner and real (random) dust particles.

 

[stebbo]

Date: 10/15/2007 4:40:01 AM
Author: Garry H (Cut Nut)

Date: 10/15/2007 4:04:49 AM
Author: stebbo

Garry, your standing makes this relative whipper-snapper always pause in questioning you, but that article:

1. Looks at the worst case by making the min and max facet opposite.
2. Looks at the worst case by assuming the tilt is exactly in the direction of the min & max facets.

Hence I say 'maximum'.

I am talking about a perfectly symmetrical diamond Stebbo.
So yes - the deviation in the top lines up with the deviation in the bottom.
But Storm would still say 'do not buy it' because it has a deviation. But it does not have a deviation.


I look at many scans of stones in DiamCalc, and I check them for deviations and they are common - and they almost always line up - the shallow side is over the steep side. Often these stones are H&A's, but the vendors do not know it because their scan data tells them the stone has lessor symmetry. The stones are fine, the scan is lousy.

Sorry, didn't notice this post before I posted above.

Yeah, with you on the overemphasis of deviation as far as optcal performance goes. Storm likes his workmanship, but I say there's greater workmanship in taming a natural substance by having to vary from geometric perfection if needed.

The shallow side often being over the steep side -> suggests the dust particle or table tilt was responsible for the majority of the deviation.

 

[Garry H (Cut Nut)]

Date: 10/15/2007 5:23:56 AM
Author: stebbo

Date: 10/15/2007 4:40:01 AM
Author: Garry H (Cut Nut)

Date: 10/15/2007 4:04:49 AM
Author: stebbo

Garry, your standing makes this relative whipper-snapper always pause in questioning you, but that article:

1. Looks at the worst case by making the min and max facet opposite.
2. Looks at the worst case by assuming the tilt is exactly in the direction of the min & max facets.

Hence I say ''maximum''.

I am talking about a perfectly symmetrical diamond Stebbo.
So yes - the deviation in the top lines up with the deviation in the bottom.
But Storm would still say ''do not buy it'' because it has a deviation. But it does not have a deviation.


I look at many scans of stones in DiamCalc, and I check them for deviations and they are common - and they almost always line up - the shallow side is over the steep side. Often these stones are H&A''s, but the vendors do not know it because their scan data tells them the stone has lessor symmetry. The stones are fine, the scan is lousy.

Sorry, didn''t notice this post before I posted above.

Yeah, with you on the overemphasis of deviation as far as optcal performance goes. Storm likes his workmanship, but I say there''s greater workmanship in taming a natural substance by having to vary from geometric perfection if needed.

The shallow side often being over the steep side -> suggests the dust particle or table tilt was responsible for the majority of the deviation.

I can not understand why this is so hard Stebbo - you should have no trouble understanding this.
It is responsible for 100.0000000000000000000000000000000000000000000000000000000000% of the deviation

 

[strmrdr]

Garry if you look at the numbers for the stone that I gave a lesser tightness score too you would see that the Crown azimuths deviation from ideal is mainly accounted for in 3 facets 2,5 and 6.
This does not support dust being under the stone, if the stone was tilted by dust it would show up there in a wider range of facets and 2 is on the opposite side of the stone.

Also putting words in my mouth is not nice I didn''t say don''t buy this diamond about either stone.

 

[stebbo]

Date: 10/15/2007 6:34:04 AM
Author: Garry H (Cut Nut)

Date: 10/15/2007 5:23:56 AM
Author: stebbo

The shallow side often being over the steep side -> suggests the dust particle or table tilt was responsible for the majority of the deviation.

I can not understand why this is so hard Stebbo - you should have no trouble understanding this.
It is responsible for 100.0000000000000000000000000000000000000000000000000000000000% of the deviation

Look at your article: Pavilion min = 40.8, Pavilion max = 42.6, deviation = 42.6 - 40.8 = 1.8 deg.
How much of it is due to tilt? 2 x 0.8 degrees = 1.6 degrees.

How is that 100%?? I'm talking real stones here like the ones you observed the scans from, not perfectly symmetrical ones. Those scans are what you commented on. Your comment is what I commented on.

We're obviously using the word 'deviation' differently as the concept is too simple to misunderstand. I know it as max - min, like a DiamCalc report shows it. It sounds to me like you're using the term to describe how much the reported angles vary from what they should really be reported as.

 

[strmrdr]

Date: 10/15/2007 11:15:58 AM
Author: stebbo

We're obviously using the word 'deviation' differently as the concept is too simple to misunderstand. I know it as max - min, like a DiamCalc report shows it. It sounds to me like you're using the term to describe how much the reported angles vary from what they should really be reported as.

What the deviation from ideal means is that if you take the crown girdle plain located at Z position above a flat surace and perfectly parellel too it and build perfect virtual diamond half around it with table X and diameter D then compare that too the actual measurements and report the differences.
The do the same with the pavilion for culet position W above the flat surface using the pavilion plain.

 

[stebbo]

Date: 10/15/2007 11:39:51 AM
Author: strmrdr
What the deviation from ideal means is that if you take the crown girdle plain located at Z position above a flat surace and perfectly parellel too it and build perfect virtual diamond half around it with table X and diameter D then compare that too the actual measurements and report the differences.

The do the same with the pavilion for culet position W above the flat surface using the pavilion plain.

That's azimuthal deviation - we're talking about simple crown angle deviations and pavilion angle deviations here, the ones you documented in red at the beginning of this thread.

 

[Paul-Antwerp]

You know, when Garry and Sergey first introduced their theory about table tilt, I did not agree with them. At that point in time, they indicated that it was rather common in production to tilt the table, and that this messed up traditional scanners, other than the Helium.

I found that they exaggerated the occurrence in production, especially in very high-quality-cuts.

Now that Garry is more stressing the occurrence as one happening while actually measuring, simply by some dust on the scanner-table, I wholeheartedly agree. It is the same effect, but another story, and to my eyes, much more plausible.

Live long,

 

[Regular Guy]

Date: 10/15/2007 4:05:12 PM
Author: Paul-Antwerp
It is the same effect, but another story, and to my eyes, much more plausible.

Live long,

I don''t suppose this helps....

 

[Garry H (Cut Nut)]

Date: 10/15/2007 4:05:12 PM
Author: Paul-Antwerp
You know, when Garry and Sergey first introduced their theory about table tilt, I did not agree with them. At that point in time, they indicated that it was rather common in production to tilt the table, and that this messed up traditional scanners, other than the Helium.

I found that they exaggerated the occurrence in production, especially in very high-quality-cuts.

Now that Garry is more stressing the occurrence as one happening while actually measuring, simply by some dust on the scanner-table, I wholeheartedly agree. It is the same effect, but another story, and to my eyes, much more plausible.

Live long,

thanks Paul
here is another example https://www.pricescope.com/community/threads/need-input-on-this-diamond-40x-ideal-scope-and-sarin-attached.70527/ that is live now

Ira I saw that last night.
I am strongly right brained, I suspect you are leftish?

 

[Regular Guy]

I guess this is what we call a side bar.

Date: 10/15/2007 4:18:30 PM
Author: Garry H (Cut Nut)

Ira I saw that last night.
I am strongly right brained, I suspect you are leftish?

Here's the analysys I posted before...which confirms the illusion, but disputes the back-story.

That is, unless...you see the man in the beans quickly!

BTW, sorry, clockwise, too. (oops...except right now...darn).

 

[gontama]

Gary - from my experience with getting multiple scans of the same stone on different occasions, it is very likley that GOG maintains one of the highest possible conditions when they scan a diamond. The "variance" remains virtualy the same, while the angles themselves slightly slide just a litttle bit. No dust. I think they are very very professional.

The only thing I have noticed for anyone to be aware is that depending on the scan "mode", p can be just slightly over 41 but is almost always 40.9X - 41.0 when scanned in another way which I believe reflects the realilty based on the BS report accompanied with it, but could very much discourage consumers because of the HCA score.

I think your finding (per octnous theory) is almost a proof that GOG stones are "extremely" tightly cut. Many of them have p variance under 0.1! So I must acknowlegde Jonathan''s ability to cherry pick a stone w/o the sacn.