Measurement accuracy choices???? A poll

[oldminer]

There are four instruments in the diamond business which create digital measurements of diamonds.

The poll makes a statement with an assumption: #1 and #2.
#3 is the question of the poll.

#1 Technology allows us to either measure with reduced machine error as diamonds get larger OR as diamonds get smaller. You can’t have it both ways.

#2 Assume that diamonds of 6.3mm diameter, about 1.00ct size, are measured equally with all present available technology.

#3 Would you opt for the highest repeatability and accuracy in measuring diamonds below or equal to 6.3mm or the highest repeatability and accuracy measuring diamonds 6.3mm and larger?

 

[Garry H (Cut Nut)]

For the information of those who need a bit - the field of view of a scanner (eg Helium) that is say 8.4mm wide by about 6mm high can only measure a stone that is max 8.3mm wide if it is placed absolute dead center on the scanners rotatng stage.

If the full feild of view is used then accuracy is at its best.

If a 4mm stone is measured then the accuracy is about half as good. 1mm and you are seriously compromised.

So scanners are made with multiple lenses that are switchable (Ogi) or removable / replaceable (Sarin) - but this introduces an error too.

BTW a princess is limited by the corner to corner size - and a 1ct marquise can be 12mm long!!!

 

[strmrdr]

placing the most accurate range to cover .5ct to 1.5ct would cover the most diamonds sold and would be my pick.

 

[Garry H (Cut Nut)]

In most larger manufacturers they have several - even 30 or 40 scanners and it is normal to have a variety of different sizes and stream the goods appropriately.

The same should be tru of larger labs.


That is also why Sergey is not interested in compromising acuracy for multi lens convenience. (Although there is another tricky alternative

)

 

[SSam]

I completely agree with strmdr. Realistically not many people buy diamonds over 1.5cts and those diamonds under 0.50cts are not usually as valuable, a less accurate measuring system should therefore be adequate for those stones.

 

[Cehrabehra]

Date: 7/12/2006 4:36:15 PM
Author:oldminer

#3 Would you opt for the highest repeatability and accuracy in measuring diamonds below or equal to 6.3mm or the highest repeatability and accuracy measuring diamonds 6.3mm and larger?

Hi David!

I''m guessing an "... and why did you vote that way" couldn''t hurt, huh?

My logic is this... if you use larger stones you can see the bigger picture in the philosophy and science behind what you do. I believe that information would be more useful to then tweak and apply toward smaller stones than to attempt to apply the technology developed for a small stone to larger stones. Look at the big picture, then fine-tune it. If you have larger stones, you can play with your parameters more and learn more about your science and craft. Small stones have small windows and tougher demands.

Besides, the people who are most interested in the technology as *consumers* are already interested in larger stones. If you want to target industry standards, you very well might be better off focusing on smaller stones for mass production. But even then I still think it''s best to look at the big picture and then go back and fine tune it for smaller stones.

 

[Cehrabehra]

Date: 7/13/2006 3:55:52 AM
Author: Sam_C
I completely agree with strmdr. Realistically not many people buy diamonds over 1.5cts and those diamonds under 0.50cts are not usually as valuable, a less accurate measuring system should therefore be adequate for those stones.

I would say though... the larger the stone, the more discerning the customer (generally)... the greater the investment... and the higher the demand for accuracy.

 

[oldminer]

Thank you for the poll results to date. Of course, there is an ulterior motive in posing this question, but it will be educational and entertaining to get some further comments before making more factual comments on the subject.

Please, any more comments?....There are no ugly surprises here, just some digital image processing information that will be of general interest.

 

[SSam]

style="WIDTH: 96.52%; HEIGHT: 107px">Date: 7/12/2006 4:36:15 PM
Author:oldminer


#3 Would you opt for the highest repeatability and accuracy in measuring diamonds below or equal to 6.3mm or the highest repeatability and accuracy measuring diamonds 6.3mm and larger?

When you say would you opt, do you mean as in ''i am a consumer'' or as in ''I''m part of the industry?'' I guess it even depends on which area of the industry you''re in. As a consumer I guess you would always want your stone to be measured by the machine the most accurate for its size. As a jewelers you would probably want the accuracy to be most accurate for the majority of the goods you sell. Even then it would depend on whether you decide to apply this to the value of your goods, the most popular or the profit made.

As a manufacturer you should have the most accuracy for all the sizes your produce. Any thoughts on this?

 

[Garry H (Cut Nut)]

Date: 7/13/2006 8:11:06 AM
Author: Sam_C
As a manufacturer you should have the most accuracy for all the sizes your produce. Any thoughts on this?

You are on the money Sam.

Most manufacturers want to be able to control their processes far more than they have a desire to cut beuatiful diamonds.
It is critical for them that they can meet their buyers needs, but just meeting them is better then exceeding them if exceding targets cost more and makes your bankers close you down.

Manufacturers like Paul are 1 in a million - they go beyond the markets needs to carve a niche for the OCD market. But even the mass amrket producer wants to know they can cut a thick but not very thick girdle every time they set out to achieve it.

 

[strmrdr]

larger facets are easier to measure until you hit the max size so if you set the point too large you lose too much on the smaller end for less gain on the large side.

 

[strmrdr]

something that will be interesting to see is how adaptive optics play out in the optical scanner field in the future.

 

[Cehrabehra]

Date: 7/13/2006 8:23:33 AM
Author: Garry H (Cut Nut)

Manufacturers like Paul are 1 in a million - they go beyond the markets needs to carve a niche for the OCD market.

LOL! I resemble that remark!

 

[whatmeworry]

David,
I''m a little unclear on what you mean by accuracy. Maybe if you gave an example that would help.

Suppose the machine measures larger stones more accurately. Would an example be that it would measure a 7mm stone plus/minus 0.01 mm and a 5 mm stone plus/minus 0.02 mm?

Although stones less than 1 ct are less valuable, I think the average size is still under 1 ct so for consumers it may be more economically beneficial for accurate measurements for smaller stones.

 

[Garry H (Cut Nut)]

Date: 7/13/2006 7:49:31 PM
Author: whatmeworry
David,
I''m a little unclear on what you mean by accuracy. Maybe if you gave an example that would help.

Suppose the machine measures larger stones more accurately. Would an example be that it would measure a 7mm stone plus/minus 0.01 mm and a 5 mm stone plus/minus 0.02 mm?

Although stones less than 1 ct are less valuable, I think the average size is still under 1 ct so for consumers it may be more economically beneficial for accurate measurements for smaller stones.

Accuracy is weird stuff when you see engineers provide the data.

I have seen how data can be miss-used, used wisely and abused.
Putting a stone on the same machine 20 times - doing the same with 20 different machines of the same type - putting the same stone on 5 different companies machines anonomously etc etc

 

[oldminer]

I do agree that all the devices do a pretty good job in the most common size range of diamonds coming into labs. (0.50ct to 1.50ct)
If all we wanted to know were measurements, then near is close enough, sort of like a shotgun at 10 feet. However, if labs and cutters are going to use measurements to estimate performance, then the more accurate the measures, the better, in theory, will be the estimates. Of course, what is not measured may well be crucial to performance, but that's another issue.

Sarin and Ogi are bringing out new units with better accuracy and Helium and ImaGem already offer these better measurements. However, three of these devices use different lenses when the stones get larger. This creates more error in measurement than using a camera with enough pixels to use the same measuring stick for any diamond put on the device. It requires a better camera and a better lens, but leads to better results in the overall. Helium uses the same camera in each of its units, but invisibly has a different lens built inside. Instead of just changing a lens, you have to buy an entire second, full unit to measure larger diamonds. Sarin and Ogi have lenses that can be changes or built in multiple stages with differing lenses, but have the same issue with error increasing as diamond size gets larger. I give Helium credit for openness in that they publish an increased error figure for potential purchasers to see before buying their device.

Please consider the economic benefits of accuracy increasing as diamond size gets larger. The higher the potential value of the diamond, the better it is measured. Folks lucky enough to get a 5ct or 10ct diamond surely don't want to have less accuracy given to them in lab reports. Cutters don't want to make costly errors in cutting due to measuring inaccuracy. I think people who responded are considering their own limited situation first and I can't blame them. If one looks at the big picture, then it becomes more apparent that it would probably be best to measure the most costly stones with the best accuracy, so long as diamonds 1/4ct and larger were properly measured. Few of us are much concerned below 1/4ct for single diamond work in labs.

 

[whatmeworry]

Where''s our resident math/econ double major? You would need to know how many buy what sizes of diamonds and what the economic "cost" is for accurate or inaccurate measurements.

Machine A: Accurate for small diamonds (+$50 benefit for buyers of small diamonds), inaccurate for large diamonds (-$800 loss to buyers of large diamonds)
Machine B: Inaccurate for small diamonds (-$75 loss to buyers of small diamonds), accurate for large diamonds ($500 benefit to buyers of large diamonds)

Diamond buying public: 4 out of 5 buy small diamonds.

Cost to the public of Machine A: -$600.00
Cost to the public of Machine B: +$200.00

I''m just making up these numbers but it could be the case that Machine A is more favorable to the diamond buying public as a whole.

 

[oldminer]

I like to see this other possible point of view or outcome stated. However, we really don''t know which scenario would occur because large diamonds are so much more valuabel than smaller ones. Smaller ones are far more numerous, for sure.

The problem with the argument is that we do not know how to calculate a coorect result based on dollars since we don''t know the market data facts. However, my side of the argument is a certainty. Larger diamonds are worth more than small ones and the impact on individual consumers of each size favors grading larger diamonds as best as possible.

 

[strmrdr]

I like the helium approach using a separate machine, there is enough profit in 5 and 10ct diamonds to justify the expense.

 

[oldminer]

Strmrdr:

You have fallen into the pit, I'm afraid. Helium is using the same camera in both machines. The difference is the lens and that is the reason Helium reports a greater error as stones get larger. It is right on their paperwork which they hand to clients. Like I said, I commend them for being aware and honest, but they cannot do the best job with the wrong camera and lens. These vendors want the trade and consumers to put full faith in their devices, but when you go from providing reasonably accurate measurements into predicting Light Behavior with those same approximate measurements, you have a large or significant problem. As far as I know, only ImaGem is advanced enough and thought through the problem sufficiently to come up with a strategy that measures all diamonds fro 1/4ct and up with the highest accuracy and repeatability.

If one takes the currently less accurate measures from a Sarin or Ogi and plugs them into the GIA Facetware tool with its rounding off issue, the final result will be doubtful................ I am being kind.

 

[Rhino]

Date: 7/13/2006 1:51:17 AM
Author: strmrdr
placing the most accurate range to cover .5ct to 1.5ct would cover the most diamonds sold and would be my pick.

Yep. .50 up to 2.5 is ideal for me.

 

[Serg]

Date: 7/14/2006 1:11:33 PM
Author: oldminer
Strmrdr:

You have fallen into the pit, I''m afraid. Helium is using the same camera in both machines. The difference is the lens and that is the reason Helium reports a greater error as stones get larger. It is right on their paperwork which they hand to clients. Like I said, I commend them for being aware and honest, but they cannot do the best job with the wrong camera and lens. These vendors want the trade and consumers to put full faith in their devices, but when you go from providing reasonably accurate measurements into predicting Light Behavior with those same approximate measurements, you have a large or significant problem. As far as I know, only ImaGem is advanced enough and thought through the problem sufficiently to come up with a strategy that measures all diamonds fro 1/4ct and up with the highest accuracy and repeatability.

If one takes the currently less accurate measures from a Sarin or Ogi and plugs them into the GIA Facetware tool with its rounding off issue, the final result will be doubtful................ I am being kind.

David,
Please explain Why are our camera and lens WRONG?
BTW

1)angle error for 12 mm round diamond on HP 1:2 analog is same like angle error for 6 mm round diamond on HP 1:1 analog .
Only linear(e.g. Diameter and height)error is bigger in two times on HP1:2. But in any case our linear error is too small( and smaller then Imagem linear error)
2) You can buy HP with digital 1600*1200 camera but it is not reasonable. More pixels do not mean better accuracy( all times) . We use subpixels algorithm.

 

[Serg]

re:These vendors want the trade and consumers to put full faith in their devices, but when you go from providing reasonably accurate measurements into predicting Light Behavior with those same approximate measurements, you have a large or significant problem.

David,
Please show such example for 3D Helium round diamond model.

 

[oldminer]

Serg;

I will see if DR. Aggarwal will provide a technical response to you early next week. I don''t want to give you a simplified response that will be improper. Like I said, I commend the honesty of your handouts and paperwork along with the relatively high accuracy of Helium. It is my belief that as liner measures deteriorate, so do angular measures, but let''s get the expert to give a conscise response.

THe isssue of predictive accuracy is a scientific argument that I have made in other threads. It falls on you and the rest of the industry to give a single example of a "grading strategy" which utilizes a "predicitve model" instead of using a "direct measuring device", when one is available for use. Maybe you have this rare example at hand, but no one to date has provided an example for discussion and debate.

I think you would admit the imperfect nature of measuring many variables versus the more sound methodology of measuring a sufficient, yet small number of variable,s which forms a conclusion with a high degree of certainty. There are measurements of a diamond you don''t take, even though you take a great number. What you don''t take may lead to differences in the end result. What you don''t measure with high accuracy may lead to a wrong result. Finally, what a lab such as GIA rounds off, not your fault, will certainly further foul up the result on occasion. It is my belief that Helium is a great measuring device and an excellent value. It is an issue with predictive use of measures to form a "GRADE" which is the objection.

I see us as competing partners in evolving and changing the diamond business for this new century. I hope you do, too.

 

[Serg]

Date: 7/15/2006 5:53:06 AM
Author: oldminer
Serg;

I will see if DR. Aggarwal will provide a technical response to you early next week. I don't want to give you a simplified response that will be improper. Like I said, I commend the honesty of your handouts and paperwork along with the relatively high accuracy of Helium. It is my belief that as liner measures deteriorate, so do angular measures, but let's get the expert to give a conscise response.

THe isssue of predictive accuracy is a scientific argument that I have made in other threads. It falls on you and the rest of the industry to give a single example of a 'grading strategy' which utilizes a 'predicitve model' instead of using a 'direct measuring device', when one is available for use. Maybe you have this rare example at hand, but no one to date has provided an example for discussion and debate.

I think you would admit the imperfect nature of measuring many variables versus the more sound methodology of measuring a sufficient, yet small number of variable,s which forms a conclusion with a high degree of certainty. There are measurements of a diamond you don't take, even though you take a great number. What you don't take may lead to differences in the end result. What you don't measure with high accuracy may lead to a wrong result. Finally, what a lab such as GIA rounds off, not your fault, will certainly further foul up the result on occasion. It is my belief that Helium is a great measuring device and an excellent value. It is an issue with predictive use of measures to form a 'GRADE' which is the objection.

I see us as competing partners in evolving and changing the diamond business for this new century. I hope you do, too.

Dave,

We are building FULL 3d model. please are not speaking like: "There are measurements of a diamond you don't take, even though you take a great number." without any proof

re:What you don't measure with high accuracy may lead to a wrong result.

Please give examples.

re:I see us as competing partners in evolving and changing the diamond business for this new century. I hope you do, too.

I can do it until you spread CORRECT information About Imagem, Helium and any other instruments and technology.

 

[oldminer]

Serg: Are you telling me there is no measure your Helium does not take? Does it take every single measurement that one can take on every diamond? Does it really measure every aspect of every facet? Does it self-calibrate by some method for each diamond?

It is my belief that I am spreading correct information. What information is incorrect?

You are being general and not specific. It sounds like you know something but won''t tell us. Why not tell us what is specifically incorrect. Does the Helium paperwork that is handed out indicate a greater machine error on larger diamonds, or do you deny that is what your handout states? Please look at what is being handed out at trade shows before you respond.

Thanks,

 

[Garry H (Cut Nut)]

Dave what Sergey is saying is that by building a 3D model of an object one can readily check with various means to see if that model is accurate. For instance a 3d model can be compared to a structured lighting like Ideal-scope, H&A''s and ASET scope. We know that Helium models are consistantly and always far better than any we have seen thus far. We have asked DR. Aggarwal to provide 3D or stl files and he has said "easy" but we have not seen any.

It is possible for any owner to scan a rough or polished stone and estimate its weight with a scanner - and then compare the result to the accurate weight. Helium gives excellent results.

So what unnamed measure is not measured?

 

[Garry H (Cut Nut)]

With regard to pixel counting - the feild of view and algorithms on the 8.4mm Helium window will measure up to a 8.4mm 2.14ct Tolkowsky stone with the highest accuracy.

A .26ct 4.2mm stone would have less accuracy, but more than any other device that has been tested in public. A 1.00ct round will have more than adequate results at 2/3rds of the feild of view.

For larger stones the same accuracy applies when a different (2:1) lens is used. The 16.8mm stone has optimum accuracy and the 8.4mm stone is not going to be measured as well. A 4.2mm stone will probably get as good or better result for accuracy as a 12mm feild of view Sarin.

When i read your thread and posts again - it seems you imagine the 2:1 system is less accurate. That is not the case.

 

[oldminer]

Imagem can, and does, make a calculation of weight in order to show it is seeing the diamond correctly, but it does not use this weight as anything. It is simply there for the record and for the user to see it is working somewhat properly. Helium is not making any use of their weight calculation, are they? Or, is Helium using a calculated weight against an actual weight from a scale to insure calibration is on target?

We know the existing ASET scope changes readings as stone get larger in relation to the angles presented to the colored cones. Aparently if the ASET scope was larger in diameter, it could provide better data accross the range of all diamonds, but in its current size even diamonds of 2 carat may not get the results of an identically fashioned 1 carat stone.

Dr. Aggarwal said it is relatively easy to build a 3D model of diamonds from measures, but he did not say he intends to build this module at any time soon. The ImaGem tool is not geared for cutters as much as for lab use. We can mine our data and provide excellent advice on re-cut and make to cutters, but no one needs a 3D model. This is more marketing than magic of some sort.

My question to Sergey was his statement about measuring everything. I was simply asking him is he sure he is measuring every single and final thing that might alter the resultant prediction. It seems impossible tha all things are measured and it seems equally unlikely that the 3D model does not have some error or hopeful adjustments built into it. He has not said otherwise.

Garry, on the accuracy issue as size increases, the Helium handouts indicate increased loss of accuracy as size gets larger. You are saying that the larger stone version is more accurate on larger diamonds than on the smaller ones it can measure. Is this something you are sure about, because the literature povided says otherwise, I believe.

 

[Serg]

re: It seems impossible tha all things are measured and it seems equally unlikely that the 3D model does not have some error or hopeful adjustments built into it. He has not said otherwise.

Of course EVERY measurement has error. Helium 3Dmodel has error too.
But i do not know about error in Helium 3dmodel round diamond( specially near classical round) Which is critical for calculation Light indexes. We developed Helium specially for our technology calculation light accuracy. We can develop and build scanner with 3-5 times better accuracy. But we and market do not need such scanner now. We can improve accuracy for our current models by using structure photos, but we do not need it yet. if you can show When our accuracy is not enough Light metrics for round classical diamond , we will improve our technology.
You did such statement SEVERAL times( for example "These vendors want the trade and consumers to put full faith in their devices, but when you go from providing reasonably accurate measurements into predicting Light Behavior with those same approximate measurements, you have a large or significant problem.
" and NEVER Proof it. You need proof it or stop it.
Did you receive correct answer?