diamond cutting questions

[WinkHPD]

I think that Storm may not have the history exactly correct, but he makes a valid point. For many years the Indians received only the basest of rough and some of the most difficult gems to cut, usually only in the smalls.

When they finally did get allocations of larger better rough, they already knew how to work with the more difficult gems, which made working with nicer material easier.

Paul is also right though, there is a very small market of cutters to whom you can sell anything, so anything new has to be priced very high to get your investment back. If Sergey could sell ten million copies of his software, it would not need to be so expensive, but I am guessing that he will sell less than 5,000 copies ever unless he discovers immortality while studying diamonds, so it must be much more expensive. (I am speaking of the Pro version.)

I reserve the right to be completely wrong about the number of copies that he sells, it is only a guess.

Wink

 

[diagem]

Date: 4/20/2008 3:26:58 PM
Author: strmrdr

Date: 4/20/2008 3:20:41 PM
Author: Paul-Antwerp

Date: 4/20/2008 2:04:00 PM
Author: strmrdr
That is how India cutters became a powerhouse by investing in R&D while nearly everyone else was sitting still.
The fear of trying new things is a huge problem for the industry.
With the margins the cutters get its not really surprising either.
But there is a lot of low color/clarity rough out there too practice on that isn''t that expensive.
Since in the old days India got a lot of these stones it may be why they were not scared too try new things as companies that got the best rough.
Not having too deal with 75 years of tradition and likely a younger workforce helped also.

Sorry, Storm, but you had a bad history-professor on this subject.

could be could be...
but outside of your own operation where are the vast majority of high tech cutting centers that use the latest and greatest?

Storm..., who were the pioneers of automated cutting machines? Pioneers of scanning and planning machines etc.., etc...?

 

[Garry H (Cut Nut)]

Date: 4/20/2008 3:38:32 PM
Author: DiaGem

Date: 4/20/2008 3:26:58 PM
Author: strmrdr

Date: 4/20/2008 3:20:41 PM
Author: Paul-Antwerp

Date: 4/20/2008 2:04:00 PM
Author: strmrdr
That is how India cutters became a powerhouse by investing in R&D while nearly everyone else was sitting still.
The fear of trying new things is a huge problem for the industry.
With the margins the cutters get its not really surprising either.
But there is a lot of low color/clarity rough out there too practice on that isn''t that expensive.
Since in the old days India got a lot of these stones it may be why they were not scared too try new things as companies that got the best rough.
Not having too deal with 75 years of tradition and likely a younger workforce helped also.

Sorry, Storm, but you had a bad history-professor on this subject.

could be could be...
but outside of your own operation where are the vast majority of high tech cutting centers that use the latest and greatest?

Storm..., who were the pioneers of automated cutting machines? Pioneers of scanning and planning machines etc.., etc...?

And who were the pioneers of the PC (IBM) and who won the fish (MS)

It is true that holders (tangs) need a lot more development (watch it happen) and that much of the cuttting technology development took and takes place outside India in Israel, Antwerp, NY and Moscow. But some large Indian sight holders have been at the forefront of computer networking and production process control to impliment various bits of high tech equipment. Many Israeli firms sell more than 1/2 their euipment into India, and many Indian firms are at the forefront of expansion into China and even now Africa.
But as Paul would say, it is not simply that my baby is more beautiful than yours

 

[Paul-Antwerp]

As much as all your points may be valid about the current industry, it has nothing to do with how India became a powerhouse.

That, my friends, has nothing to do with cutting, technology or anything closely related to it. It is a result of financing, marketing, using loopholes in an antiquated governmental system, and so on. And while I am thinking about it, there are at least a dozen other reasons too, but none of them has anything to do with cutting and definitely not technology.

Live long,

 

[diagem]

Date: 4/20/2008 3:54:46 PM
Author: Garry H (Cut Nut)

Date: 4/20/2008 3:38:32 PM
Author: DiaGem

Date: 4/20/2008 3:26:58 PM
Author: strmrdr

Date: 4/20/2008 3:20:41 PM
Author: Paul-Antwerp

Date: 4/20/2008 2:04:00 PM
Author: strmrdr
That is how India cutters became a powerhouse by investing in R&D while nearly everyone else was sitting still.
The fear of trying new things is a huge problem for the industry.
With the margins the cutters get its not really surprising either.
But there is a lot of low color/clarity rough out there too practice on that isn''t that expensive.
Since in the old days India got a lot of these stones it may be why they were not scared too try new things as companies that got the best rough.
Not having too deal with 75 years of tradition and likely a younger workforce helped also.

Sorry, Storm, but you had a bad history-professor on this subject.

could be could be...
but outside of your own operation where are the vast majority of high tech cutting centers that use the latest and greatest?

Storm..., who were the pioneers of automated cutting machines? Pioneers of scanning and planning machines etc.., etc...?

And who were the pioneers of the PC (IBM) and who won the fish (MS)

It is true that holders (tangs) need a lot more development (watch it happen) and that much of the cuttting technology development took and takes place outside India in Israel, Antwerp, NY and Moscow. But some large Indian sight holders have been at the forefront of computer networking and production process control to impliment various bits of high tech equipment. Many Israeli firms sell more than 1/2 their euipment into India, and many Indian firms are at the forefront of expansion into China and even now Africa.
But as Paul would say, it is not simply that my baby is more beautiful than yours

Only?? What about polishing wheels, true balanced cutting tables or floors, polishing techniques and materials for the super smooth EXXXXX polish everybody is looking for, cooling technologies for risky rough material etc..., etc...?

Like I said..., we are still very primitive..., yes..., the technology is getting there but it wont help without the right adaption of tools to compliment that technology...

 

[strmrdr]

Date: 4/20/2008 4:04:19 PM
Author: Paul-Antwerp
As much as all your points may be valid about the current industry, it has nothing to do with how India became a powerhouse.

That, my friends, has nothing to do with cutting, technology or anything closely related to it. It is a result of financing, marketing, using loopholes in an antiquated governmental system, and so on. And while I am thinking about it, there are at least a dozen other reasons too, but none of them has anything to do with cutting and definitely not technology.

Live long,

point taken Paul, I see where you are coming from.

 

[Garry H (Cut Nut)]

Date: 4/20/2008 4:05:29 PM
Author: DiaGem

Date: 4/20/2008 3:54:46 PM
Author: Garry H (Cut Nut)

And who were the pioneers of the PC (IBM) and who won the fish (MS)

It is true that holders (tangs) need a lot more development (watch it happen) and that much of the cuttting technology development took and takes place outside India in Israel, Antwerp, NY and Moscow. But some large Indian sight holders have been at the forefront of computer networking and production process control to impliment various bits of high tech equipment. Many Israeli firms sell more than 1/2 their euipment into India, and many Indian firms are at the forefront of expansion into China and even now Africa.
But as Paul would say, it is not simply that my baby is more beautiful than yours

Only?? What about polishing wheels, true balanced cutting tables or floors, polishing techniques and materials for the super smooth EXXXXX polish everybody is looking for, cooling technologies for risky rough material etc..., etc...?

Like I said..., we are still very primitive..., yes..., the technology is getting there but it wont help without the right adaption of tools to compliment that technology...

I have seen the most amazing granite slabs that would make kitchens to die for used for vibration damping

 

[strmrdr]

Date: 4/20/2008 4:05:29 PM
Author: DiaGem
Only?? What about polishing wheels, true balanced cutting tables or floors, polishing techniques and materials for the super smooth EXXXXX polish everybody is looking for, cooling technologies for risky rough material etc..., etc...?

Like I said..., we are still very primitive..., yes..., the technology is getting there but it wont help without the right adaption of tools to compliment that technology...

all of those engineering problems have been solved many times over.
All it would take is someone too apply them to the diamond problem.
But the industry shuts out the vast majority of people with the skills too do it.
There is limited cottage industry in diamond cutting where the technical innovations come from due too the high barrier of entry.
All the money is in marketing.

 

[strmrdr]

BTW if anyone wants too tackle them come to my city and hire the laid off aerospace engineers and the expert machinist who is working at the hardware store because his job went too china.

 

[beryl]

Date: 4/19/2008 10:12:00 PM
Author:ydiamonds
Just curious and have a couple questions for the diamond cutting experts.

With all the advances in technology, why are diamonds still cut by hand? Wouldn't a computer be able to determine the best cut for a rough, and then cut it more precisely and perfectly for a given objective?

Secondly, what factors determine how well a diamond is polished? Why can't all diamonds have excellent polish?

Thanks.

This is the simple original question; somehow the issue got lost.
Garry has answered it well and so has Paul (Infinity). Brian Gavin (WhiteFlash) discussed this extensively - recall the long discussion 2 years ago about 'yawed' facets.
As a cutter of colored stones I can comment to the idea of automatically-cut stones. It has been done effectively on synthetic stones with perfect preforms (waste involved). However, each natural stone should be cut to maximize its potential and to accommodate its structural idiosyncracies - no two are alike.
Garry's mention of Princess cuts where polishing may be almost parallel to the cleavage planes, and Paul's about gripping the stone show real familiarity with the problems.

 

[ydiamonds]

Thanks for the education everyone. You''ve all been most helpful and I appreciate the insight.

 

[diagem]

Date: 4/20/2008 11:37:52 PM
Author: beryl

Date: 4/19/2008 10:12:00 PM
Author:ydiamonds
Just curious and have a couple questions for the diamond cutting experts.

With all the advances in technology, why are diamonds still cut by hand? Wouldn''t a computer be able to determine the best cut for a rough, and then cut it more precisely and perfectly for a given objective?

Secondly, what factors determine how well a diamond is polished? Why can''t all diamonds have excellent polish?

Thanks.

This is the simple original question; somehow the issue got lost.
Garry has answered it well and so has Paul (Infinity). Brian Gavin (WhiteFlash) discussed this extensively - recall the long discussion 2 years ago about ''yawed'' facets.
As a cutter of colored stones I can comment to the idea of automatically-cut stones. It has been done effectively on synthetic stones with perfect preforms (waste involved). However, each natural stone should be cut to maximize its potential and to accommodate its structural idiosyncracies - no two are alike.
Garry''s mention of Princess cuts where polishing may be almost parallel to the cleavage planes, and Paul''s about gripping the stone show real familiarity with the problems.

So if for example (not realistic but lets imagine a perfect world), you could get your hands on perfect octahedron''s (crystals all clean and evenly shaped), it could have been automatically cut by machines (to all the necessary cutting stages)?

 

[Garry H (Cut Nut)]

Date: 4/21/2008 12:53:06 AM
Author: DiaGem

Date: 4/20/2008 11:37:52 PM
Author: beryl

This is the simple original question; somehow the issue got lost.
Garry has answered it well and so has Paul (Infinity). Brian Gavin (WhiteFlash) discussed this extensively - recall the long discussion 2 years ago about ''yawed'' facets.
As a cutter of colored stones I can comment to the idea of automatically-cut stones. It has been done effectively on synthetic stones with perfect preforms (waste involved). However, each natural stone should be cut to maximize its potential and to accommodate its structural idiosyncracies - no two are alike.
Garry''s mention of Princess cuts where polishing may be almost parallel to the cleavage planes, and Paul''s about gripping the stone show real familiarity with the problems.

So if for example (not realistic but lets imagine a perfect world), you could get your hands on perfect octahedron''s (crystals all clean and evenly shaped), it could have been automatically cut by machines (to all the necessary cutting stages)?

The Apollo people did a presentation while I was in India last year. They were promoting the idea of making CVD diamonds to preformed shapes in volume for Indian factories to polish.
Of course what they should be doing is finding the technology, not the manual labour, to do just as Beryl suggests

There would be a huge entry level market in China and India, and in a few years in Africa too.

 

[diagem]

Date: 4/21/2008 3:05:36 AM
Author: Garry H (Cut Nut)

Date: 4/21/2008 12:53:06 AM
Author: DiaGem

Date: 4/20/2008 11:37:52 PM
Author: beryl

This is the simple original question; somehow the issue got lost.
Garry has answered it well and so has Paul (Infinity). Brian Gavin (WhiteFlash) discussed this extensively - recall the long discussion 2 years ago about ''yawed'' facets.
As a cutter of colored stones I can comment to the idea of automatically-cut stones. It has been done effectively on synthetic stones with perfect preforms (waste involved). However, each natural stone should be cut to maximize its potential and to accommodate its structural idiosyncracies - no two are alike.
Garry''s mention of Princess cuts where polishing may be almost parallel to the cleavage planes, and Paul''s about gripping the stone show real familiarity with the problems.

So if for example (not realistic but lets imagine a perfect world), you could get your hands on perfect octahedron''s (crystals all clean and evenly shaped), it could have been automatically cut by machines (to all the necessary cutting stages)?

The Apollo people did a presentation while I was in India last year. They were promoting the idea of making CVD diamonds to preformed shapes in volume for Indian factories to polish.
Of course what they should be doing is finding the technology, not the manual labour, to do just as Beryl suggests

There would be a huge entry level market in China and India, and in a few years in Africa too.

So synthetic yes ---- natural no?

BTW..., the problem with cutting/polishing Diamonds parallel to the natural cleavage plane can be easily solved...

 

[Garry H (Cut Nut)]

electricity?

 

[diagem]

Simpler...

 

[Garry H (Cut Nut)]

You win?

 

[diagem]

Date: 4/21/2008 4:13:11 AM
Author: Garry H (Cut Nut)
You win?

I DID

??? WOW!!!

 

[strmrdr]

Date: 4/21/2008 4:06:01 AM
Author: DiaGem
Simpler...

never mind... not till I get a patent :}

 

[Serg]

Date: 4/20/2008 7:26:15 AM
Author: Garry H (Cut Nut)

Date: 4/20/2008 7:21:55 AM
Author: strmrdr

Date: 4/20/2008 7:15:40 AM
Author: DiaGem
Garry..., what is the visual difference between an excellent polish and good polish IF you dont use optic tools to check?

I have seen good graded polish on a crown facet of a EC give it a frosted look on that facet in some lighting that was eye visible.
In other stones where it was a pavilion facet when looking at it lose you could see the frosted effect but face up it was not apparent.
That is why when calling in stones I say to avoid good polish on step cuts because you don''t know what facet it is and the effect it will have.

A perfect example of my dislike for ''features'' based grading Storm.

I would prefer benefit based grading.
We will get there.
It might take decades

Quality surface( flatness and polishing quality ) is very important for brightness of Flashes , specially if distance between diamond and observer is big

 

[diagem]

Date: 4/21/2008 6:09:04 AM
Author: Serg

Date: 4/20/2008 7:26:15 AM
Author: Garry H (Cut Nut)

Date: 4/20/2008 7:21:55 AM
Author: strmrdr

Date: 4/20/2008 7:15:40 AM
Author: DiaGem
Garry..., what is the visual difference between an excellent polish and good polish IF you dont use optic tools to check?

I have seen good graded polish on a crown facet of a EC give it a frosted look on that facet in some lighting that was eye visible.
In other stones where it was a pavilion facet when looking at it lose you could see the frosted effect but face up it was not apparent.
That is why when calling in stones I say to avoid good polish on step cuts because you don''t know what facet it is and the effect it will have.

A perfect example of my dislike for ''features'' based grading Storm.

I would prefer benefit based grading.
We will get there.
It might take decades

Quality surface( flatness and polishing quality ) is very important for brightness of Flashes , specially if distance between diamond and observer is big

Serg..., how big...?

Do you honestly claim that minor polishing lines/fissures will effect the flashes to a noticeable extent that can be differentiated by unaided vision?
Interesting..., and I would be interested to hearing more...

 

[Serg]

Date: 4/21/2008 6:20:18 AM
Author: DiaGem

Date: 4/21/2008 6:09:04 AM
Author: Serg

Date: 4/20/2008 7:26:15 AM
Author: Garry H (Cut Nut)

Date: 4/20/2008 7:21:55 AM
Author: strmrdr

Date: 4/20/2008 7:15:40 AM
Author: DiaGem
Garry..., what is the visual difference between an excellent polish and good polish IF you dont use optic tools to check?

I have seen good graded polish on a crown facet of a EC give it a frosted look on that facet in some lighting that was eye visible.
In other stones where it was a pavilion facet when looking at it lose you could see the frosted effect but face up it was not apparent.
That is why when calling in stones I say to avoid good polish on step cuts because you don''t know what facet it is and the effect it will have.

A perfect example of my dislike for ''features'' based grading Storm.

I would prefer benefit based grading.
We will get there.
It might take decades

Quality surface( flatness and polishing quality ) is very important for brightness of Flashes , specially if distance between diamond and observer is big

Serg..., how big...?

Do you honestly claim that minor polishing lines/fissures will effect the flashes to a noticeable extent that can be differentiated by unaided vision?
Interesting..., and I would be interested to hearing more...

Diagem,

Take distance between source light and observer 3 meters. Pupil size will 0.01 degree

Take 1 ct round cut

Width of girdle pavilion facet is 400 microns
If flatness is 5 microns
Roundness of pavilion facets will 0.7 degree

Such non flat facets will spread energy from 0.01 degree to 1.5 degree. Brightness will in 100 times less

Of course it is very draft calculations for WHITE flash ( for color flash result will in 2-3 times less only) and real roundness could be much less
It is just simple example why flatness is so critical and why diamond could have much more bright flashes than CZ

 

[diagem]

Date: 4/21/2008 7:08:44 AM
Author: Serg

Date: 4/21/2008 6:20:18 AM
Author: DiaGem

Date: 4/21/2008 6:09:04 AM
Author: Serg

Date: 4/20/2008 7:26:15 AM
Author: Garry H (Cut Nut)

Date: 4/20/2008 7:21:55 AM
Author: strmrdr

Date: 4/20/2008 7:15:40 AM
Author: DiaGem
Garry..., what is the visual difference between an excellent polish and good polish IF you dont use optic tools to check?

I have seen good graded polish on a crown facet of a EC give it a frosted look on that facet in some lighting that was eye visible.
In other stones where it was a pavilion facet when looking at it lose you could see the frosted effect but face up it was not apparent.
That is why when calling in stones I say to avoid good polish on step cuts because you don''t know what facet it is and the effect it will have.

A perfect example of my dislike for ''features'' based grading Storm.

I would prefer benefit based grading.
We will get there.
It might take decades

Quality surface( flatness and polishing quality ) is very important for brightness of Flashes , specially if distance between diamond and observer is big

Serg..., how big...?

Do you honestly claim that minor polishing lines/fissures will effect the flashes to a noticeable extent that can be differentiated by unaided vision?
Interesting..., and I would be interested to hearing more...

Diagem,

Take distance between source light and observer 3 meters. Pupil size will 0.01 degree

Take 1 ct round cut

Width of girdle pavilion facet is 400 microns
If flatness is 5 microns
Roundness of pavilion facets will 0.7 degree

Such non flat facets will spread energy from 0.01 degree to 1.5 degree. Brightness will in 100 times less

Of course it is very draft calculations for WHITE flash ( for color flash result will in 2-3 times less only) and real roundness could be much less
It is just simple example why flatness is so critical and why diamond could have much more bright flashes than CZ

Ok..., let see if I understand you correctly...

What would be the difference in flatness between an excellent polish and a good polish surface?

 

[Garry H (Cut Nut)]

Date: 4/21/2008 7:26:46 AM
Author: DiaGem

Date: 4/21/2008 7:08:44 AM
Author: Serg

Date: 4/21/2008 6:20:18 AM
Author: DiaGem

Date: 4/21/2008 6:09:04 AM
Author: Serg

Date: 4/20/2008 7:26:15 AM
Author: Garry H (Cut Nut)

Date: 4/20/2008 7:21:55 AM
Author: strmrdr

Date: 4/20/2008 7:15:40 AM
Author: DiaGem
Garry..., what is the visual difference between an excellent polish and good polish IF you dont use optic tools to check?

I have seen good graded polish on a crown facet of a EC give it a frosted look on that facet in some lighting that was eye visible.
In other stones where it was a pavilion facet when looking at it lose you could see the frosted effect but face up it was not apparent.
That is why when calling in stones I say to avoid good polish on step cuts because you don't know what facet it is and the effect it will have.

A perfect example of my dislike for 'features' based grading Storm.

I would prefer benefit based grading.
We will get there.
It might take decades

Quality surface( flatness and polishing quality ) is very important for brightness of Flashes , specially if distance between diamond and observer is big

Serg..., how big...?

Do you honestly claim that minor polishing lines/fissures will effect the flashes to a noticeable extent that can be differentiated by unaided vision?
Interesting..., and I would be interested to hearing more...

Diagem,

Take distance between source light and observer 3 meters. Pupil size will 0.01 degree

Take 1 ct round cut

Width of girdle pavilion facet is 400 microns
If flatness is 5 microns
Roundness of pavilion facets will 0.7 degree

Such non flat facets will spread energy from 0.01 degree to 1.5 degree. Brightness will in 100 times less

Of course it is very draft calculations for WHITE flash ( for color flash result will in 2-3 times less only) and real roundness could be much less
It is just simple example why flatness is so critical and why diamond could have much more bright flashes than CZ

Ok..., let see if I understand you correctly...

What would be the difference in flatness between an excellent polish and a good polish surface?

DiaGem this is Drena's diamond sitting between my keys on keyboard facing the halogen bulb directly above me - maybe 2M away. I took this just now, adjusted exposure a little.
Note you can see the little dot dot dots from the ring clip that holds the halogen in place.
The larger white zone is the out of focus table - but I made the camera focus on long distance

Get the idea?
You can read the writting on a bulb across the other side of the room.
Sergey showed me this trick in a great little hotel restaruant in Germany 3 years ago.

 

[diagem]

Date: 4/21/2008 8:22:05 AM
Author: Garry H (Cut Nut)

DiaGem this is Drena''s diamond sitting between my keys on keyboard facing the halogen bulb directly above me - maybe 2M away. I took this just now, adjusted exposure a little.
Note you can see the little dot dot dots from the ring clip that holds the halogen in place.
The larger white zone is the out of focus table - but I made the camera focus on long distance

Get the idea?
You can read the writting on a bulb across the other side of the room.
Sergey showed me this trick in a great little hotel restaruant in Germany 3 years ago.

Ok..., and you can see these fine miniscule features only reflecting from a EX polish and not on a good one?

Or am I off-track?

 

[Serg]

Date: 4/21/2008 9:06:50 AM
Author: DiaGem

Date: 4/21/2008 8:22:05 AM
Author: Garry H (Cut Nut)

DiaGem this is Drena''s diamond sitting between my keys on keyboard facing the halogen bulb directly above me - maybe 2M away. I took this just now, adjusted exposure a little.
Note you can see the little dot dot dots from the ring clip that holds the halogen in place.
The larger white zone is the out of focus table - but I made the camera focus on long distance

Get the idea?
You can read the writting on a bulb across the other side of the room.
Sergey showed me this trick in a great little hotel restaruant in Germany 3 years ago.

Ok..., and you can see these fine miniscule features only reflecting from a EX polish and not on a good one?

Or am I off-track?

take 2 diamonds with good and bad polish ( or CZ)
use white paper to see reflections from diamond facets( ETAS)
For same distance between diamond and paper , reflections from bad polishing diamond will more dull

 

[diagem]

Date: 4/21/2008 11:48:24 AM
Author: Serg

Date: 4/21/2008 9:06:50 AM
Author: DiaGem

Date: 4/21/2008 8:22:05 AM
Author: Garry H (Cut Nut)

DiaGem this is Drena''s diamond sitting between my keys on keyboard facing the halogen bulb directly above me - maybe 2M away. I took this just now, adjusted exposure a little.
Note you can see the little dot dot dots from the ring clip that holds the halogen in place.
The larger white zone is the out of focus table - but I made the camera focus on long distance

Get the idea?
You can read the writting on a bulb across the other side of the room.
Sergey showed me this trick in a great little hotel restaruant in Germany 3 years ago.

Ok..., and you can see these fine miniscule features only reflecting from a EX polish and not on a good one?

Or am I off-track?

take 2 diamonds with good and bad polish ( or CZ)
use white paper to see reflections from diamond facets( ETAS)
For same distance between diamond and paper , reflections from bad polishing diamond will more dull

Yes true..., but the difference will not be visible to the unaided eye on a good and excellent polish..., I believe..

 

[Garry H (Cut Nut)]

Date: 4/21/2008 1:02:22 PM
Author: DiaGem

Date: 4/21/2008 11:48:24 AM
Author: Serg

Date: 4/21/2008 9:06:50 AM
Author: DiaGem

Date: 4/21/2008 8:22:05 AM
Author: Garry H (Cut Nut)

DiaGem this is Drena''s diamond sitting between my keys on keyboard facing the halogen bulb directly above me - maybe 2M away. I took this just now, adjusted exposure a little.
Note you can see the little dot dot dots from the ring clip that holds the halogen in place.
The larger white zone is the out of focus table - but I made the camera focus on long distance

Get the idea?
You can read the writting on a bulb across the other side of the room.
Sergey showed me this trick in a great little hotel restaruant in Germany 3 years ago.

Ok..., and you can see these fine miniscule features only reflecting from a EX polish and not on a good one?

Or am I off-track?

take 2 diamonds with good and bad polish ( or CZ)
use white paper to see reflections from diamond facets( ETAS)
For same distance between diamond and paper , reflections from bad polishing diamond will more dull

Yes true..., but the difference will not be visible to the unaided eye on a good and excellent polish..., I believe..

DG I think we best all try sergey''s experiment and report back.
If you can see the diffference then your red statement above is wrong

But I do know what you meant to say.
lets do it anyway

 

[diagem]

Date: 4/21/2008 5:38:14 PM
Author: Garry H (Cut Nut)

Date: 4/21/2008 1:02:22 PM
Author: DiaGem

Date: 4/21/2008 11:48:24 AM
Author: Serg

Date: 4/21/2008 9:06:50 AM
Author: DiaGem

Date: 4/21/2008 8:22:05 AM
Author: Garry H (Cut Nut)

DiaGem this is Drena''s diamond sitting between my keys on keyboard facing the halogen bulb directly above me - maybe 2M away. I took this just now, adjusted exposure a little.
Note you can see the little dot dot dots from the ring clip that holds the halogen in place.
The larger white zone is the out of focus table - but I made the camera focus on long distance

Get the idea?
You can read the writting on a bulb across the other side of the room.
Sergey showed me this trick in a great little hotel restaruant in Germany 3 years ago.

Ok..., and you can see these fine miniscule features only reflecting from a EX polish and not on a good one?

Or am I off-track?

take 2 diamonds with good and bad polish ( or CZ)
use white paper to see reflections from diamond facets( ETAS)
For same distance between diamond and paper , reflections from bad polishing diamond will more dull

Yes true..., but the difference will not be visible to the unaided eye on a good and excellent polish..., I believe..

DG I think we best all try sergey''s experiment and report back.
If you can see the diffference then your red statement above is wrong

But I do know what you meant to say.
lets do it anyway

OK...,

, dont reveal to anyone

.

 

[beryl]

Date: 4/21/2008 12:53:06 AM
Author: DiaGem

Date: 4/20/2008 11:37:52 PM
Author: beryl

Date: 4/19/2008 10:12:00 PM
Author:ydiamonds
Just curious and have a couple questions for the diamond cutting experts.

With all the advances in technology, why are diamonds still cut by hand? Wouldn''t a computer be able to determine the best cut for a rough, and then cut it more precisely and perfectly for a given objective?

Secondly, what factors determine how well a diamond is polished? Why can''t all diamonds have excellent polish?

Thanks.

This is the simple original question; somehow the issue got lost.
Garry has answered it well and so has Paul (Infinity). Brian Gavin (WhiteFlash) discussed this extensively - recall the long discussion 2 years ago about ''yawed'' facets.
As a cutter of colored stones I can comment to the idea of automatically-cut stones. It has been done effectively on synthetic stones with perfect preforms (waste involved). However, each natural stone should be cut to maximize its potential and to accommodate its structural idiosyncracies - no two are alike.
Garry''s mention of Princess cuts where polishing may be almost parallel to the cleavage planes, and Paul''s about gripping the stone show real familiarity with the problems.

So if for example (not realistic but lets imagine a perfect world), you could get your hands on perfect octahedron''s (crystals all clean and evenly shaped), it could have been automatically cut by machines (to all the necessary cutting stages)?

DiaGem:
Theoretically this would be possible. Because the round gem is coming from ''square'' rough, the time spent on similar facets of different orientation would vary; it would be a tricky piece of programming.
My hearing of automatic cutting was synthetic corundum in a perfectly round conical preform. Even then, if you cut them in sequence around the preform the time is longer for the first facet than for the last (machines are not perfectly rigid so the time varies slightly according to the amount of stock being removed - what is called ''sparkout'' in the precision grinding industry). It would be necessary to program for cutting facets alternately on opposite sides of the stone instead of sequentially around it. Circa 1980 I did cutting-time tests for DuPont diamond grit vs natural & GE; these factors became very apparent in trying to get consistent test results.
In the case of the synthetic corundum preforms, I also heard that they were using large cylindrical drums to produce near-flat facets, because a flat lap tends to produce convex facets if you polish too fast (polish flowing under facet). Also flat laps tend to wear concave, producing convex facets (I will only try a step-cut stone immediately after re-surfacing a flat lap because it wears concave too fast).
In reality, I think there are too many variables to make the discussion worthwhile. Brian Gavin must have much to say on this. I can imagine what Gaby Tolkowsky would say.