Why depth is not the opposite of spread in a fancy shape?

[denverappraiser]

Garry,

Do not confuse value with price. Price is set by sellers, which is what you’re doing using a diamcalc algorithhm, and it can be whatever the seller or the programmers wants to ask. Value is set by buyers and their behavior in the market and is driven by what buyers are willing to pay for various things under the circumstances at hand. These are definitely not the same thing. Buyers may or may not value the same things and in the same ways that you do when you set your prices and using a program to tell them what they should want is fraught with trouble.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[Garry H (Cut Nut)]

Date: 3/29/2010 7:43:26 PM
Author: denverappraiser
Garry,

Do not confuse value with price. Price is set by sellers, which is what you’re doing using a diamcalc algorithhm, and it can be whatever the seller or the programmers wants to ask. Value is set by buyers and their behavior in the market and is driven by what buyers are willing to pay for various things under the circumstances at hand. These are definitely not the same thing. Buyers may or may not value the same things and in the same ways that you do when you set your prices and using a program to tell them what they should want is fraught with trouble.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

This is not a price fixing approach Neil, it is more to relate fancy values to those of round brilliants which are a better value based market.
And it means that there is then a reward incentive for designers to create desirable shapes and not rip consumers off with frozen spit cut quality and huge yeild / small spread.

 

[denverappraiser]

It IS a price fixing approach. You are, of course, welcome to do that but it presumes what the customers will count as important and in what relation they wish to compare it to other things. This is a huge assumption. It’s not only inventing a grading scale based on what you and Sergey count as ‘better’ about one stone over another but it measures that preference in terms of price. Using a grading scale to encourage cutters to produce stones that score well on it is exactly the complaint that Stan is bringing up above regarding the ACA charts but at least these don’t attach a price. Let the market forces do that, they will anyway.

Neither value nor prices are gemological properties and they have no place in DiamCalc.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[Garry H (Cut Nut)]

Date: 3/29/2010 9:35:06 PM
Author: denverappraiser
It IS a price fixing approach. You are, of course, welcome to do that but it presumes what the customers will count as important and in what relation they wish to compare it to other things. This is a huge assumption. It’s not only inventing a grading scale based on what you and Sergey count as ‘better’ about one stone over another but it measures that preference in terms of price. Using a grading scale to encourage cutters to produce stones that score well on it is exactly the complaint that Stan is bringing up above regarding the ACA charts but at least these don’t attach a price. Let the market forces do that, they will anyway.

Neither value nor prices are gemological properties and they have no place in DiamCalc.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

Neil it is simply making a price link between fancy shapes and rounds.
Given that round solitaire sized stones were about 50% of the market, and since the GFC they have grown to maybe 55 or even 60% of the market, it seems to make sense to link the two.

There is no price fixing in that. The market for rounds is way too big.

As to making a method to compare the spread and some appearace aspects of rounds and fancy shapes - and sure - that is right on the current topic with Dave''s AGA charts. As to how it could be done using the DiamCalc Basic Light Return functions - we are in early days, and there is plenty of time for discussion, and it could probably be a topic at the Second Diamond Cut Conference that we are now planning for August next year (we postponed the one arranged for Luasanne Swistzerland this year because of the GFC). Since only users of DiamCalcPro have full access to the entire suit of information, there would need to be some sharing perhaps with other parties.

For a start those who would like to know more can download the free DiamCalc Demo version
http://www.octonus.ru/oct/download/diam_demo_down.phtml
It only has a Marquise, but you can use some fire predictors and ETAS and DETAS qualitative data.

Of course any other lab or organisation can impliment any other approach they wish to as well. But OctoNus clients have a huge advantage because DiamCalc is so deeply integrated into the rough diamond planning process.

 

[Karl_K]

Date: 3/29/2010 7:26:06 PM
Author: Garry H (Cut Nut)

Next Diamond has a plan to calculate diamond values based on a simple (for Sergey and Janak) algorithm that uses spread and basic light return information to calculate a value (as always - compared to a Tolkowsky round). This would do away with the rather silly range of discounts that apply in the trade with round and pear shaped Rapaport price lists.

Frankly no one has any business nor the right to try setting the price I sell my custom designed diamonds for. (other than the cutter who tells me the production/rough/his profit costs which sets the low end base)

1> spread Fred I can name a dozen of designs I would give up some spread for. One example is one you have made a big push for in the past.. FIC
2> DC light return stereo is an important criteria for my designs I will not deny that.
I will not compromise the other design criteria to meet an arbitrary standard that has no relation to the diamond design in question however.
Diamond brightness is only a small part of diamond beauty/performance.
A computer can tell you a diamonds performance but it can not grade its beauty.
A designs beauty comes from my ability to translate computer images/information/calculations to what the finished product should look like then decide if it is beautiful or if I should move on.
Then it must be cut and verified.

 

[Garry H (Cut Nut)]

Nobody will be forced to sell diamond via Next Diamond Karl.

 

[Paul-Antwerp]

Date: 3/29/2010 7:26:06 PM
Author: Garry H (Cut Nut)

Date: 3/29/2010 5:08:58 PM
Author: oldminer

If someone wants to prove that theoretically a diamond can have a strange combination of AGA 1 characterisitcs and still not look nice, I imagine it can be accomplished,
I have taken the challenge Dave

I agree with the majority here that a trusted, qualified vendor is the best partner for a diamond consumer. There are many vendors here who I believe consumers can trust to lead them in the right direction.
The problem there is choosing which vendor to trust the most with which shape etc. I prefer consumer friendly systems to vendor based and innefficient shipping of goods hither and thither.

Gentlemen I am going to make Paul cross again with a ‘politicial’ pronouncement for a solution to this dilemma.

The image below shows an extreme example of two ovals, one cushionish, where the table and depth % are the same.
Same LXW, same gidrdle thickness, but look at the two weights and spread data in the lower right of each DiamCalc window.

AGS also adopted this spread approach that we developed for DiamCalc.
And for some inhouse stones we have adopted a similar approach on Pricescope (but it only works for a few sahpoes because we can not see the outline.

Sergey agrees that we should put this into information into Gem Adviser to protect consumers.

Next Diamond has a plan to calculate diamond values based on a simple (for Sergey and Janak) algorithm that uses spread and basic light return information to calculate a value (as always - compared to a Tolkowsky round). This would do away with the rather silly range of discounts that apply in the trade with round and pear shaped Rapaport price lists.

(This political announcement was authorized by the Peoples Consumer Rights Party)

Hey Garry,

I would not know why this would make me cross. You are just confirming that it is impossible to predict spread from depth-% alone, and that another method should be used. You are even confirming that while trying to use a real spread-measure, you have to limit yourself to in-house-stones and to a few shapes, for obvious reasons.

The fact that you feel the need to add a business-announcement is your problem. Too many announcements about how major changes will come about, without anything seemingly happening, only hurt your reputation. As a friend, I advice you more caution.

Live long,

 

[Garry H (Cut Nut)]

Date: 3/30/2010 5:18:45 AM
Author: Paul-Antwerp

Hey Garry,

You are just confirming that it is impossible to predict spread from depth-% alone, and that another method should be used. You are even confirming that while trying to use a real spread-measure, you have to limit yourself to in-house-stones and to a few shapes, for obvious reasons.

Live long,

Paul do you know of any other way, let alone a better way, than using DiamCalc (and Gem Adviser in the next release) to calculate the spread?

How else can you compute spread for out of round round diamonds and different curvature or corner in cushions and asschers etc?

If you agree then all we need to do is find out how to get more stones made available where this information is available. And if we request it for all fancy shapes - both B2B and C2B - then we can also solve a lot of problems.

In addition - the very painstakingly slow development work that you allude to - is at last beginning to show fruits as more and more OctoNus clients make this info available - notably led by Venus Jewel who is a trail blazing company. They list Gem Adviser files on all there stones on their website. On most stones they have a Helium report, which they use for all the hard to scan stones.

 

[Garry H (Cut Nut)]

After an off-line discussion I should just clarify:
GOG and Infinity have for some years given Gem Adviser files on all stones (except proprietary designs to stop copying).
The point I made regarding Venus is they are the first very large manufacturer to list B2B (they do not sell B2C, and do not accept returns, so they also do not feed drop shipping). This means they are not a direct feed to Pricescope consumers. Other leading Indian companies will also supply .gem or .dmc files, however they do not list them on their B2B sites. One large company that could do this is a supplier of Blue Nile, but I doubt that Blue Nile is ready for this level of transparency (and staff training).

Will there be less companies listing GA .gem files, or more, in the future? Surely it will be more?
The answer as to how quickly depends mostly on how quickly OctoNus can institute inclusion generation and viewing tools - I saw a demo 2 weeks ago that was promising, but the R&D to makes digital inclusions appear realistic (semi transparent, clouds etc are tough to do) is incredibly difficult. The GFC did not help.

But surely once inclusions are available in Gem files, the demand will be strong. At present there are many hundreds of engagement ring and large diamonds being planned and polished every day using equipment that plots and photographs every inclusion with a 115x microscope as part of the value optimisation process. The manufacturers would naturally prefer to use thoes inclusion plots to assist in selling the diamond.

 

[originalradiantman]

I agree with Garry that a vehicle that provides more accurate spread comparisons among diamonds would be an extremely useful tool for consumers, and I wish the gem labs would incorporate this kind of data, which is objective and measurable, into their reports. However, any attempt to correlate that information to value or price would be subjective and arbitrary since spread is only one component in a very complicated and ultimately personal evaluation.

Also, benchmarking fancies based on a "performance" measure established for rounds is wrong in so many ways that its hard to know where to start. It assumes that a "well cut" round is by definition has the most pleasing appearance in terms of how it reflects light, and that the goal of all fancy shapes is to approximate the look of a round as much as possible. In my opinion, this is simply untrue. People do not only choose fancies because they prefer the shape - they choose fancies because they prefer the overall look including the manner in which light is reflected.

Oldminer - manufacturers (other than those whose business is based on specific quality standards) cut diamonds based on how the rough lies. You don''t cut a square peg into a round hole because the economics won''t let you.

The diamond that I described that would meet your requirements for a 1A while being small looking and/or ugly is not a theoretical figment of my imagination. It exists in the real world in not insubstantial quantities not because the cutter sets out to make an ugly diamond, but because that''s how the rough lies and because bad benchmarks create a real economic incentive to do so.

Achieving a depth % benchmark the "wrong" way often costs less weight than doing it the "right" way. Doing this often leads to an uglier diamond than one that failed to meet the benchmark, but it may be "worth" more because consumers incorrectly believe the benchmark means something it doesn''t.

I think that''s the point that Paul made earlier when he said that misconceptions about depth% distort the cutting process and limit consumer choices and in my opinion he is 100% correct.

 

[ChunkyCushionLover]

Date: 3/30/2010 8:25:44 PM
Author: Garry H (Cut Nut)

Date: 3/30/2010 5:18:45 AM
Author: Paul-Antwerp

Hey Garry,

You are just confirming that it is impossible to predict spread from depth-% alone, and that another method should be used. You are even confirming that while trying to use a real spread-measure, you have to limit yourself to in-house-stones and to a few shapes, for obvious reasons.

Live long,

Paul do you know of any other way, let alone a better way, than using DiamCalc (and Gem Adviser in the next release) to calculate the spread?

How else can you compute spread for out of round round diamonds and different curvature or corner in cushions and asschers etc?

If you agree then all we need to do is find out how to get more stones made available where this information is available. And if we request it for all fancy shapes - both B2B and C2B - then we can also solve a lot of problems.

In addition - the very painstakingly slow development work that you allude to - is at last beginning to show fruits as more and more OctoNus clients make this info available - notably led by Venus Jewel who is a trail blazing company. They list Gem Adviser files on all there stones on their website. On most stones they have a Helium report, which they use for all the hard to scan stones.

Garry,

Could you please elaborate on exactly how Diamcalc is calculating girdle plain spread for fancy shapes.

 

[Garry H (Cut Nut)]

Date: 3/31/2010 11:43:26 AM
Author: ChunkyCushionLover

Date: 3/30/2010 8:25:44 PM
Author: Garry H (Cut Nut)

Date: 3/30/2010 5:18:45 AM
Author: Paul-Antwerp

Hey Garry,

You are just confirming that it is impossible to predict spread from depth-% alone, and that another method should be used. You are even confirming that while trying to use a real spread-measure, you have to limit yourself to in-house-stones and to a few shapes, for obvious reasons.

Live long,

Paul do you know of any other way, let alone a better way, than using DiamCalc (and Gem Adviser in the next release) to calculate the spread?

How else can you compute spread for out of round round diamonds and different curvature or corner in cushions and asschers etc?

If you agree then all we need to do is find out how to get more stones made available where this information is available. And if we request it for all fancy shapes - both B2B and C2B - then we can also solve a lot of problems.

In addition - the very painstakingly slow development work that you allude to - is at last beginning to show fruits as more and more OctoNus clients make this info available - notably led by Venus Jewel who is a trail blazing company. They list Gem Adviser files on all there stones on their website. On most stones they have a Helium report, which they use for all the hard to scan stones.

Garry,

Could you please elaborate on exactly how Diamcalc is calculating girdle plain spread for fancy shapes.

Yes, they have really smart software developers!
Exactly how is probably beyond my small brain CCL

 

[Paul-Antwerp]

Garry,

Sorry for the late reply, I still need to answer your question. You asked if I know any better way than Diamcalc to calculate the spread.

Well, I do not, but using Diamcalc implies a necessity to have a full scan of the stone, something that is currently not available for the stones listed virtually. Even if one could ask for it, it is impractical unless after a first selection.

So, for now, even if one can use Diamcalc to measure spread exactly, it will not help anyone looking at the multiple options on the virtual list.

In that sense, the original topic of this thread is important. One might be inclined to use depth as a selection-criterium, but that is flawed. Better would be to look at actual diameters. Although that is not perfect, because of the problem of curvature and cut-corners, it at least gives a better idea than the depth-percentage.

Live long,

 

[WinkHPD]

Date: 3/29/2010 10:23:01 PM
Author: Garry H (Cut Nut)

Date: 3/29/2010 9:35:06 PM
Author: denverappraiser
It IS a price fixing approach. You are, of course, welcome to do that but it presumes what the customers will count as important and in what relation they wish to compare it to other things. This is a huge assumption. It’s not only inventing a grading scale based on what you and Sergey count as ‘better’ about one stone over another but it measures that preference in terms of price. Using a grading scale to encourage cutters to produce stones that score well on it is exactly the complaint that Stan is bringing up above regarding the ACA charts but at least these don’t attach a price. Let the market forces do that, they will anyway.

Neither value nor prices are gemological properties and they have no place in DiamCalc.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

Neil it is simply making a price link between fancy shapes and rounds.
Given that round solitaire sized stones were about 50% of the market, and since the GFC they have grown to maybe 55 or even 60% of the market, it seems to make sense to link the two.

There is no price fixing in that. The market for rounds is way too big.

As to making a method to compare the spread and some appearace aspects of rounds and fancy shapes - and sure - that is right on the current topic with Dave''s AGA charts. As to how it could be done using the DiamCalc Basic Light Return functions - we are in early days, and there is plenty of time for discussion, and it could probably be a topic at the Second Diamond Cut Conference that we are now planning for August next year (we postponed the one arranged for Luasanne Swistzerland this year because of the GFC). Since only users of DiamCalcPro have full access to the entire suit of information, there would need to be some sharing perhaps with other parties.

For a start those who would like to know more can download the free DiamCalc Demo version
http://www.octonus.ru/oct/download/diam_demo_down.phtml
It only has a Marquise, but you can use some fire predictors and ETAS and DETAS qualitative data.

Of course any other lab or organisation can impliment any other approach they wish to as well. But OctoNus clients have a huge advantage because DiamCalc is so deeply integrated into the rough diamond planning process.

Gary,

You know I have tremendous respect for you but Neil is quite right. You are attempting to link the price of apples to the price of oranges and it is not only wrong, but in my opinion unethical. The Octonus software is stunning in the things that it does right, why would you now want to build into it a componenent that is simply wrong for its purpose. Let your software tell us how the gem will look, I am sure it was an important tool for Karl to develope his beautiful diamond, but it could not ever tell him how much he has to charge to make a reasonable profit.

As my Southern friends like to say, "That dog don''t hunt!"

Wink

 

[Garry H (Cut Nut)]

Date: 4/1/2010 9:57:40 AM
Author: Wink

Date: 3/29/2010 10:23:01 PM
Author: Garry H (Cut Nut)

Date: 3/29/2010 9:35:06 PM
Author: denverappraiser
It IS a price fixing approach. You are, of course, welcome to do that but it presumes what the customers will count as important and in what relation they wish to compare it to other things. This is a huge assumption. It’s not only inventing a grading scale based on what you and Sergey count as ‘better’ about one stone over another but it measures that preference in terms of price. Using a grading scale to encourage cutters to produce stones that score well on it is exactly the complaint that Stan is bringing up above regarding the ACA charts but at least these don’t attach a price. Let the market forces do that, they will anyway.

Neither value nor prices are gemological properties and they have no place in DiamCalc.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

Neil it is simply making a price link between fancy shapes and rounds.
Given that round solitaire sized stones were about 50% of the market, and since the GFC they have grown to maybe 55 or even 60% of the market, it seems to make sense to link the two.

There is no price fixing in that. The market for rounds is way too big.

As to making a method to compare the spread and some appearace aspects of rounds and fancy shapes - and sure - that is right on the current topic with Dave''s AGA charts. As to how it could be done using the DiamCalc Basic Light Return functions - we are in early days, and there is plenty of time for discussion, and it could probably be a topic at the Second Diamond Cut Conference that we are now planning for August next year (we postponed the one arranged for Luasanne Swistzerland this year because of the GFC). Since only users of DiamCalcPro have full access to the entire suit of information, there would need to be some sharing perhaps with other parties.

For a start those who would like to know more can download the free DiamCalc Demo version
http://www.octonus.ru/oct/download/diam_demo_down.phtml
It only has a Marquise, but you can use some fire predictors and ETAS and DETAS qualitative data.

Of course any other lab or organisation can impliment any other approach they wish to as well. But OctoNus clients have a huge advantage because DiamCalc is so deeply integrated into the rough diamond planning process.

Gary,

You know I have tremendous respect for you but Neil is quite right. You are attempting to link the price of apples to the price of oranges and it is not only wrong, but in my opinion unethical. The Octonus software is stunning in the things that it does right, why would you now want to build into it a componenent that is simply wrong for its purpose. Let your software tell us how the gem will look, I am sure it was an important tool for Karl to develope his beautiful diamond, but it could not ever tell him how much he has to charge to make a reasonable profit.

As my Southern friends like to say, ''That dog don''t hunt!''

Wink

Hi Wink, looking forward to catching up in Vegas - it will be before we know it!

DiamCalc does actually have a Rap or any other price list importing function, but what we are discussing here is a Next Diamond pricing solution that will only effect participants in Next Diamond.
There should be no attempt to see this as having any influence on any other part of the industry.

UNLESS it is successful - and then it may have an impact.

But what we would like to see is a method of transparency on pricing so that consumers should know what to expect, and manufacturers and designers would be predictably rewarded for creativity and fine cutting and polishing.

 

[ChunkyCushionLover]

Date: 3/29/2010 7:26:06 PM
Author: Garry H (Cut Nut)

Date: 3/29/2010 5:08:58 PM
Author: oldminer

If someone wants to prove that theoretically a diamond can have a strange combination of AGA 1 characterisitcs and still not look nice, I imagine it can be accomplished,
I have taken the challenge Dave

I agree with the majority here that a trusted, qualified vendor is the best partner for a diamond consumer. There are many vendors here who I believe consumers can trust to lead them in the right direction.
The problem there is choosing which vendor to trust the most with which shape etc. I prefer consumer friendly systems to vendor based and innefficient shipping of goods hither and thither.

Gentlemen I am going to make Paul cross again with a ‘politicial’ pronouncement for a solution to this dilemma.

The image below shows an extreme example of two ovals, one cushionish, where the table and depth % are the same.
Same LXW, same gidrdle thickness, but look at the two weights and spread data in the lower right of each DiamCalc window.

AGS also adopted this spread approach that we developed for DiamCalc.
And for some inhouse stones we have adopted a similar approach on Pricescope (but it only works for a few sahpoes because we can not see the outline.

Sergey agrees that we should put this into information into Gem Adviser to protect consumers.

Next Diamond has a plan to calculate diamond values based on a simple (for Sergey and Janak) algorithm that uses spread and basic light return information to calculate a value (as always - compared to a Tolkowsky round). This would do away with the rather silly range of discounts that apply in the trade with round and pear shaped Rapaport price lists.

(This political announcement was authorized by the Peoples Consumer Rights Party)

What do you mean? Considering I have downloaded the demo and am considering a purchase, this is one of many questions I had and I couldn't find it on the Octonus website. I'd like to know how accurately the program can account for rounded corners in cushions and other near square shapes for the purposes of spread calculation and comparison.

 

[Serg]

Date: 4/2/2010 12:14:13 PM
Author: ChunkyCushionLover

Date: 3/29/2010 7:26:06 PM

Author: Garry H (Cut Nut)

Date: 3/29/2010 5:08:58 PM

Author: oldminer


If someone wants to prove that theoretically a diamond can have a strange combination of AGA 1 characterisitcs and still not look nice, I imagine it can be accomplished,

I have taken the challenge Dave

I agree with the majority here that a trusted, qualified vendor is the best partner for a diamond consumer. There are many vendors here who I believe consumers can trust to lead them in the right direction.

The problem there is choosing which vendor to trust the most with which shape etc. I prefer consumer friendly systems to vendor based and innefficient shipping of goods hither and thither.

Gentlemen I am going to make Paul cross again with a ‘politicial’ pronouncement for a solution to this dilemma.


The image below shows an extreme example of two ovals, one cushionish, where the table and depth % are the same.

Same LXW, same gidrdle thickness, but look at the two weights and spread data in the lower right of each DiamCalc window.


AGS also adopted this spread approach that we developed for DiamCalc.

And for some inhouse stones we have adopted a similar approach on Pricescope (but it only works for a few sahpoes because we can not see the outline.


Sergey agrees that we should put this into information into Gem Adviser to protect consumers.


Next Diamond has a plan to calculate diamond values based on a simple (for Sergey and Janak) algorithm that uses spread and basic light return information to calculate a value (as always - compared to a Tolkowsky round). This would do away with the rather silly range of discounts that apply in the trade with round and pear shaped Rapaport price lists.


(This political announcement was authorized by the Peoples Consumer Rights Party)

What do you mean? Considering I have downloaded the demo and am considering a purchase, this is one of many questions I had and I couldn't find it on the Octonus website. I'd like to know how accurately the program can account for rounded corners in cushions and other near square shapes for the purposes of spread calculation and comparison.

links for documentation about parameters

spread

DC movie with inclusions

 

[Serg]

Date: 3/31/2010 11:25:59 AM
Author: originalradiantman
I agree with Garry that a vehicle that provides more accurate spread comparisons among diamonds would be an extremely useful tool for consumers, and I wish the gem labs would incorporate this kind of data, which is objective and measurable, into their reports. However, any attempt to correlate that information to value or price would be subjective and arbitrary since spread is only one component in a very complicated and ultimately personal evaluation.


Also, benchmarking fancies based on a ''performance'' measure established for rounds is wrong in so many ways that its hard to know where to start. It assumes that a ''well cut'' round is by definition has the most pleasing appearance in terms of how it reflects light, and that the goal of all fancy shapes is to approximate the look of a round as much as possible. In my opinion, this is simply untrue. People do not only choose fancies because they prefer the shape - they choose fancies because they prefer the overall look including the manner in which light is reflected.


Oldminer - manufacturers (other than those whose business is based on specific quality standards) cut diamonds based on how the rough lies. You don''t cut a square peg into a round hole because the economics won''t let you.


The diamond that I described that would meet your requirements for a 1A while being small looking and/or ugly is not a theoretical figment of my imagination. It exists in the real world in not insubstantial quantities not because the cutter sets out to make an ugly diamond, but because that''s how the rough lies and because bad benchmarks create a real economic incentive to do so.



Achieving a depth % benchmark the ''wrong'' way often costs less weight than doing it the ''right'' way. Doing this often leads to an uglier diamond than one that failed to meet the benchmark, but it may be ''worth'' more because consumers incorrectly believe the benchmark means something it doesn''t.


I think that''s the point that Paul made earlier when he said that misconceptions about depth% distort the cutting process and limit consumer choices and in my opinion he is 100% correct.

Hi Stan,

I want clarify Garry statement about connection between spread, performance and price.
we need it to select most promised solution during allocation( before cutting) for NEW cuts( Market price for New cuts is absent )
then when these new cuts come to market , price of course will depends from consumer demand also
but in beginning of life for new cuts we do not know better method to evaluate price for these NEW cuts.
Do anybody know any way how cutter could select cuts during allocation process without pricelist?

 

[ChunkyCushionLover]

Date: 4/2/2010 4:04:16 PM
Author: Serg

Date: 4/2/2010 12:14:13 PM
Author: ChunkyCushionLover

Date: 3/29/2010 7:26:06 PM

Author: Garry H (Cut Nut)

Date: 3/29/2010 5:08:58 PM

Author: oldminer


If someone wants to prove that theoretically a diamond can have a strange combination of AGA 1 characterisitcs and still not look nice, I imagine it can be accomplished,

I have taken the challenge Dave

I agree with the majority here that a trusted, qualified vendor is the best partner for a diamond consumer. There are many vendors here who I believe consumers can trust to lead them in the right direction.

The problem there is choosing which vendor to trust the most with which shape etc. I prefer consumer friendly systems to vendor based and innefficient shipping of goods hither and thither.

Gentlemen I am going to make Paul cross again with a ‘politicial’ pronouncement for a solution to this dilemma.


The image below shows an extreme example of two ovals, one cushionish, where the table and depth % are the same.

Same LXW, same gidrdle thickness, but look at the two weights and spread data in the lower right of each DiamCalc window.


AGS also adopted this spread approach that we developed for DiamCalc.

And for some inhouse stones we have adopted a similar approach on Pricescope (but it only works for a few sahpoes because we can not see the outline.


Sergey agrees that we should put this into information into Gem Adviser to protect consumers.


Next Diamond has a plan to calculate diamond values based on a simple (for Sergey and Janak) algorithm that uses spread and basic light return information to calculate a value (as always - compared to a Tolkowsky round). This would do away with the rather silly range of discounts that apply in the trade with round and pear shaped Rapaport price lists.


(This political announcement was authorized by the Peoples Consumer Rights Party)

What do you mean? Considering I have downloaded the demo and am considering a purchase, this is one of many questions I had and I couldn''t find it on the Octonus website. I''d like to know how accurately the program can account for rounded corners in cushions and other near square shapes for the purposes of spread calculation and comparison.

links for documentation about parameters

spread

DC movie with inclusions

Yes I read this link before, except that what is the diameter in a Fancy Cut Diamond? What I want is the surface area of the girdle plain.

 

[Serg]

re:Yes I read this link before, except that what is the diameter in a Fancy Cut Diamond? What I want is the surface area of the girdle plain.

this link has two definitions . one for OctoNus spread, other for AGS spread

OctoNus spread does not use diameter, we use only surface area

AGS uses diameter and it is work only for Round cuts

 

[ChunkyCushionLover]

Date: 4/3/2010 1:14:47 AM
Author: Serg
re:Yes I read this link before, except that what is the diameter in a Fancy Cut Diamond? What I want is the surface area of the girdle plain.

this link has two definitions . one for OctoNus spread, other for AGS spread

OctoNus spread does not use diameter, we use only surface area

AGS uses diameter and it is work only for Round cuts

How does DiamCalc calculate girdle plain surface area for any fancy shape? Is there a way it accounts for the rounded corners?
I don''t see surface area in mm squared being listed, only a spread listed in a % that I assume compares its spread to the same carat weight tolkowsky round.

 

[Serg]

Date: 4/3/2010 1:28:47 AM
Author: ChunkyCushionLover

Date: 4/3/2010 1:14:47 AM

Author: Serg

re:Yes I read this link before, except that what is the diameter in a Fancy Cut Diamond? What I want is the surface area of the girdle plain.


this link has two definitions . one for OctoNus spread, other for AGS spread


OctoNus spread does not use diameter, we use only surface area



AGS uses diameter and it is work only for Round cuts

How does DiamCalc calculate girdle plain surface area for any fancy shape? Is there a way it accounts for the rounded corners?

I don''t see surface area in mm squared being listed, only a spread listed in a % that I assume compares its spread to the same carat weight tolkowsky round.

CCL,
re:How does DiamCalc calculate girdle plain surface area for any fancy shape? Is there a way it accounts for the rounded corners?
firstly we project all facets in to girdle plan, then sum areas of all facets. It is easy. strange what you are asking it
this approach has not any problems with rounded corners if step of scanning is 0.9 degree( or even 2 degree). just check difference in area for ideal cycle and ideal 400 points polygon
our spread is difference in MASS between your diamond and RBC with same area.

 

[diagem]

Shouldnt CH be taken into consideration when comparing spread?
When calculating SQ-mm of face up area..., is a bulging crown calculated as well?

 

[Serg]

Date: 4/3/2010 3:02:25 AM
Author: DiaGem
Shouldnt CH be taken into consideration when comparing spread?

When calculating SQ-mm of face up area..., is a bulging crown calculated as well?

Yoram, we compare visible area from FaceUp direction( strongly perpendicularly to table facet)

Girdle side spread is different issue. There are two types visual spread: FaceUp and Girdle side.
Unfortunately diamond market is not use well even FaceUp spread, and if we add Girdle side spread now it will even more confusing .
we need move step by step

 

[diagem]

Date: 4/3/2010 3:19:42 AM
Author: Serg

Date: 4/3/2010 3:02:25 AM
Author: DiaGem
Shouldnt CH be taken into consideration when comparing spread?

When calculating SQ-mm of face up area..., is a bulging crown calculated as well?

Yoram, we compare visible area from FaceUp direction( strongly perpendicularly to table facet)

Girdle side spread is different issue. There are two types visual spread: FaceUp and Girdle side.
Unfortunately diamond market is not use well even FaceUp spread, and if we add Girdle side spread now it will even more confusing .
we need move step by step

Both are novice to ''Diamond'' market...
They are perpendicular and for the spread info to be meaningful the Girdle Side must be taken into consideration.
We are witnessing more new & old designs being cut consisting higher CH''s

Its easier sometimes to kill 2 birds with 1 stone....

, these 2 birds can be educated together (IMO).

 

[Garry H (Cut Nut)]

I agree with both of you.

I have long suggested that high crown diamonds also have an apparent spread advantage. But Yoram it is not as pronounced as the outline spread - so lets get this factor up and running and then discuss the weighting for verticle spread

 

[diagem]

Date: 4/3/2010 4:25:46 AM
Author: Garry H (Cut Nut)
I agree with both of you.

I have long suggested that high crown diamonds also have an apparent spread advantage. But Yoram it is not as pronounced as the outline spread - so lets get this factor up and running and then discuss the weighting for verticle spread

Oh..., ok

.

 

[whatmeworry]

Serg and Garry,
Unless you take vertical spread into account at the same time, then you would only be penalizing (for lack of horizontal spread) without rewarding vertical spread. So something like the Antwerp Twins cut would be penalized without any reward.

I think the horizontal(face-up) spread is something like -9% for a round. I haven''t seen any of these yet and I don''t know if they will be popular, but I applaud them for bringing something new.

As an exercise, you could see what you would price something like this at with your system and see if that makes sense.

 

[whatmeworry]

Date: 4/3/2010 2:20:10 PM
Author: whatmeworry
Serg and Garry,

Unless you take vertical spread into account at the same time, then you would only be penalizing (for lack of horizontal spread) without rewarding vertical spread. So something like the Antwerp Twins cut would be penalized without any reward.


I think the horizontal(face-up) spread is something like -9% for a round. I haven''t seen any of these yet and I don''t know if they will be popular, but I applaud them for bringing something new.


As an exercise, you could see what you would price something like this at with your system and see if that makes sense.

Correction, the diameter is -9% but the equivalent round would weigh about -22% less.

 

[Garry H (Cut Nut)]

Date: 4/3/2010 2:20:10 PM
Author: whatmeworry
Serg and Garry,
Unless you take vertical spread into account at the same time, then you would only be penalizing (for lack of horizontal spread) without rewarding vertical spread. So something like the Antwerp Twins cut would be penalized without any reward.

I think the horizontal(face-up) spread is something like -9% for a round. I haven''t seen any of these yet and I don''t know if they will be popular, but I applaud them for bringing something new.

As an exercise, you could see what you would price something like this at with your system and see if that makes sense.

So what factor would you propose WMW? (it alos has an extremely deep pavilion if the image is to scale)