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

[Serg]

re:The 1ct has more spread per ct which is a fact...

Exactly !

How is misleading what diamonds with exactly same proportions have Different "Spread"?
How is helpful such "spread"? "Spread" what mainly gives preference for bigger diamonds?
"Spread" what helps bigger diamonds to hide Real negative Spread( due deep pavilion, moon facets, etc)
will such "Spread" protect consumers? Help to do best choice?
for my opinion it is not useless only moreover it is very misleading and confusing . It is one reason why we do not use such "Spread" in OctoNus products

 

[Karl_K]

Date: 4/13/2010 12:04:53 PM
Author: Serg
re:The 1ct has more spread per ct which is a fact...


Exactly !


How is misleading what diamonds with exactly same proportions have Different ''Spread''?

How is helpful such ''spread''? ''Spread'' what mainly gives preference for bigger diamonds?

''Spread'' what helps bigger diamonds to hide Real negative Spread( due deep pavilion, moon facets, etc)

will such ''Spread'' protect consumers? Help to do best choice?

for my opinion it is not useless only moreover it is very misleading and confusing . It is one reason why we do not use such ''Spread'' in OctoNus products

When used to compare apples to apples it is good.
When comparing apples to oranges your system is better.

You system does not answer how much bigger is this 1ct than this 1.2ct it says that the spread is the same.
Consumers want 2 things:
Which is bigger? Is it eye visible?
Is it in the correct mm range for the cut and weight?

That a round has better OctoNus Spread than a princess is irrelevant to many people.
They want a princess cut.

 

[oldminer]

There are now two kinds of "spread" being discussed. Do the following agree with the two concepts in this thread?

#1 is Comparative Spread which is useful to answer the common question of "Which diamond looks larger?" This is used with diamonds of similar or identical weight. The result is a simple square mm number for each diamond.

#2 is Relative Spread which allows diamonds of quite different weights to be compared to a 1ct standard round Ideal cut in terms of effective use of their carat weight to visual size ratio when compared to their square mm girdle plane size. The result is a percentage or ratio of the tested diamond to a standard 1 carat round diamond in terms of visual size.

 

[Serg]

Date: 4/13/2010 12:53:12 PM
Author: Karl_K

Date: 4/13/2010 12:04:53 PM

Author: Serg

re:The 1ct has more spread per ct which is a fact...



Exactly !



How is misleading what diamonds with exactly same proportions have Different ''Spread''?


How is helpful such ''spread''? ''Spread'' what mainly gives preference for bigger diamonds?


''Spread'' what helps bigger diamonds to hide Real negative Spread( due deep pavilion, moon facets, etc)


will such ''Spread'' protect consumers? Help to do best choice?


for my opinion it is not useless only moreover it is very misleading and confusing . It is one reason why we do not use such ''Spread'' in OctoNus products

When used to compare apples to apples it is good.

When comparing apples to oranges your system is better.


You system does not answer how much bigger is this 1ct than this 1.2ct it says that the spread is the same.

Consumers want 2 things:

Which is bigger? Is it eye visible?

Is it in the correct mm range for the cut and weight?


That a round has better OctoNus Spread than a princess is irrelevant to many people.

They want a princess cut.

in such case lets consider case: apples to apples

6.0mm round 0.8 ct has bigger sq mm/per carat than 6.3mm round 0.9 ct( both ASG0)
but OctoNus spread is bigger for 6.3 mm round 0.9 ct?

What is more helpful ?
what does sq mm/per carat say in such case?
Octonus spread say
1) 6.3 round 0.9 ct uses mass better for visual size appearance
2) if you take parameters as 6.3 mm 0.9 ct round but 6.0mm diamonds you will pay for less carats( 0.77ct instead 0.8ct) and receive same visual size as 6.0mm 0.8ct

 

[Serg]

second image for previous post

 

[Serg]

re:You system does not answer how much bigger is this 1ct than this 1.2ct it says that the spread is the same.
Consumers want 2 things:
Which is bigger? Is it eye visible?
Is it in the correct mm range for the cut and weight?
----
1)sq.mm/carat does not give answer which is bigger if mass are different( sq.mm does)
2)sq.mm/carat does not give answer for: "Is it eye visible"
3)sq.mm/carat does not give answer for ''Is it in the correct mm range for the cut and weight?''( OctoNus spread does)

re:That a round has better OctoNus Spread than a princess is irrelevant to many people.
They want a princess cut.

--
if consumer compare 1 ct round and 1 ct princess he will receive same advice from Both systems( sq.mm/carat an octonus spread). Sq.mm/carat works only for same masses
OctoNus spread give real opportunities for consumer :
1) Compare Princess with different proportions and different masses( sq.mm/per does not do it)
2) Compare visual size for different cuts

So if masses for both diamonds are same asnwer from both systems are same, if masses are different sq.mm/per carat could give wrong answer at all( OctoNus spread are correct for any masses)

 

[ChunkyCushionLover]

Date: 4/13/2010 2:03:41 PM
Author: Serg
re:You system does not answer how much bigger is this 1ct than this 1.2ct it says that the spread is the same.
Consumers want 2 things:
Which is bigger? Is it eye visible?
Is it in the correct mm range for the cut and weight?
----
1)sq.mm/carat does not give answer which is bigger if mass are different( sq.mm does)
2)sq.mm/carat does not give answer for: 'Is it eye visible'
3)sq.mm/carat does not give answer for 'Is it in the correct mm range for the cut and weight?'( OctoNus spread does)

re:That a round has better OctoNus Spread than a princess is irrelevant to many people.
They want a princess cut.

--
if consumer compare 1 ct round and 1 ct princess he will receive same advice from Both systems( sq.mm/carat an octonus spread). Sq.mm/carat works only for same masses
OctoNus spread give real opportunities for consumer :
1) Compare Princess with different proportions and different masses( sq.mm/per does not do it)
2) Compare visual size for different cuts

So if masses for both diamonds are same asnwer from both systems are same, if masses are different sq.mm/per carat could give wrong answer at all( OctoNus spread are correct for any masses)

It has already been mentioned that surface area in mm square / carat weight is only useful when comparing stones of the same mass so lets focus on surface area in mm squared only.


If you you look at mm squared you can judge the faceup size difference between any two diamonds period, many who like numbers can do it just by looking at the two numbers as they are directly comparable. If you want to know the size difference in % then using the same formula as in Octonus spread.

% Difference in Faceup Area:

1 = diamond of interest
2 = reference diamond

(SA1 - SA2)/SA1*100

1) Tells you relative size difference if masses are difference
2) Tells you relative size difference if mass is the same but faceup sizes is different due to design
3) Tells you relaitve size difference between different LW ratios if mass is different or if mass is the same

It answers all the questions one would like to know, the only missing piece of information is the surface area of the reference.

In Diamcalc you have just defined 2 as a particular tolk diamond with the same weight as 1, the consumer or vendor may prefer to choose whatever reference they like for the comparison.
Reference could be an ideal stone in that particular outline shape (compare princess with princess), a diamond with particular facet design or just two diamonds available for purchase.

You are rigidly telling us the only possible reference is the tolk round. One could argue that an appropriate reference is required for each shape outline or facet design.

 

[Serg]

re;You are very rigidly telling us the only possible reference is the tolk round.

I never say it.( please give link when I did it)
reference diamond could be any. It is not very important because octonus spread is relative

if first princess has Octonus spread -15%, and second Princess has OctoNus spread -10%, you can compare these two Princess and say what second princess has better spread.

Same answer will if you change reference diamond .
So in principal you can use any reference diamond in OctoNus Spread approach . I prefer Tolk cut just because it is more transparent for more consumers.


re:One could argue that an appropriate reference is required for each shape outline or facet design.


I am strongly disagree with such approach because result is much more less transparent and useful for consumer. same problems when you compare Light performance of Princes with Princess only. For consumer is more interesting compare Light performance all cuts with one reference, when you can understand what cuts has bigger Light performance: Round, Princess, Cushion?

same for Spread. On reference is more transparent approach

 

[ChunkyCushionLover]

Date: 4/13/2010 2:42:36 PM
Author: Serg
re;You are very rigidly telling us the only possible reference is the tolk round.

I never say it.( please give link when I did it)
reference diamond could be any. It is not very important because octonus spread is relative

if first princess has Octonus spread -15%, and second Princess has OctoNus spread -10%, you can compare these two Princess and say what second princess has better spread.

Same answer will if you change reference diamond .
So in principal you can use any reference diamond in OctoNus Spread approach . I prefer Tolk cut just because it is more transparent for more consumers.

By not listing surface area in mm square, you have rigidly forced any end user to copy down your Tolk cut paramters, plug them into Diamcalc to get the diameter and thus surface area of the reference round. This is a backwards way of getting the surface area of the diamond of interest when it could be leasily listed as a line in the output.

You cannot directly compare Octonus Spread percentages to get relative size difference if the carat weight is slightly different, which it usually is in real world comparisons.

 

[Serg]

Date: 4/13/2010 2:50:22 PM
Author: ChunkyCushionLover

Date: 4/13/2010 2:42:36 PM

Author: Serg

re;You are very rigidly telling us the only possible reference is the tolk round.


I never say it.( please give link when I did it)

reference diamond could be any. It is not very important because octonus spread is relative


if first princess has Octonus spread -15%, and second Princess has OctoNus spread -10%, you can compare these two Princess and say what second princess has better spread.


Same answer will if you change reference diamond .

So in principal you can use any reference diamond in OctoNus Spread approach . I prefer Tolk cut just because it is more transparent for more consumers.

By not listing surface area in mm square, you have rigidly forced any end user to copy down your Tolk cut paramters, plug them into Diamcalc to get the diameter and thus surface area of the reference round. This is a backwards way of getting the surface area of the diamond of interest when it could be leasily listed as a line in the output.


You cannot directly compare Octonus Spread percentages to get relative size difference if the carat weight is slightly different, which it usually is in real world comparisons.

Did you read end page 4?
"How is misleading what diamonds with exactly same proportions have Different ''Spread''?

How is helpful such ''spread''? ''Spread'' what mainly gives preference for bigger diamonds?

''Spread'' what helps bigger diamonds to hide Real negative Spread( due deep pavilion, moon facets, etc)

will such ''Spread'' protect consumers? Help to do best choice?

for my opinion it is not useless only moreover it is very misleading and confusing . It is one reason why we do not use such ''Spread'' in OctoNus products"

 

[ChunkyCushionLover]

Date: 4/13/2010 2:52:48 PM
Author: Serg

Date: 4/13/2010 2:50:22 PM
Author: ChunkyCushionLover

Date: 4/13/2010 2:42:36 PM

Author: Serg

re;You are very rigidly telling us the only possible reference is the tolk round.


I never say it.( please give link when I did it)

reference diamond could be any. It is not very important because octonus spread is relative


if first princess has Octonus spread -15%, and second Princess has OctoNus spread -10%, you can compare these two Princess and say what second princess has better spread.


Same answer will if you change reference diamond .

So in principal you can use any reference diamond in OctoNus Spread approach . I prefer Tolk cut just because it is more transparent for more consumers.

By not listing surface area in mm square, you have rigidly forced any end user to copy down your Tolk cut paramters, plug them into Diamcalc to get the diameter and thus surface area of the reference round. This is a backwards way of getting the surface area of the diamond of interest when it could be leasily listed as a line in the output.


You cannot directly compare Octonus Spread percentages to get relative size difference if the carat weight is slightly different, which it usually is in real world comparisons.

Did you read end page 4?
'How is misleading what diamonds with exactly same proportions have Different 'Spread'?

How is helpful such 'spread'? 'Spread' what mainly gives preference for bigger diamonds?

'Spread' what helps bigger diamonds to hide Real negative Spread( due deep pavilion, moon facets, etc)

will such 'Spread' protect consumers? Help to do best choice?

for my opinion it is not useless only moreover it is very misleading and confusing . It is one reason why we do not use such 'Spread' in OctoNus products'

Serg,

You think comparing the relative surface areas of a cushion (something with rounded corners where one cannot use simply geomtry to calculate SA) that is 1.05 carats with a Octonus spread of -3% with another cushion of 1 carat with Octonus spread of +2% is misleading and confusing? (The two have the same price which one is bigger?)

I know comparing Octonus spread of the two would be misleading and confusing, one could not add the % difference in Octonus spread to get relative sizes.

But taking the difference in the surface areas as a % of the two would be accurate.

 

[Serg]

re:You think comparing the relative surface areas of a cushion (something with rounded corners where one cannot use simply geomtry to calculate SA) that is 1.05 carats with a Octonus spread of -3% with another cushion of 1 carat with Octonus spread of +2% is misleading and confusing? (The two have the same price which one is bigger?)

Two days ago I had plans to add square area in DC exactly for same task, but after last 2 days discussion in PS forum I understood what it could be big mistake. A lot of in trade and consumers will use it to calculate "spread"=sq.mm/ct what will give misleading and confusing results for a lot of cases.

 

[Serg]

re:You think comparing the relative surface areas of a cushion (something with rounded corners where one cannot use simply geomtry to calculate SA) that is 1.05 carats with a Octonus spread of -3% with another cushion of 1 carat with Octonus spread of +2% is misleading and confusing? (The two have the same price which one is bigger?)

1.05 ct with octonus spread -3%( roughly 0.03ct)=1.02 tolk round
1.00 ct with Octonus spreas +2%( rougly 0.02ct) =1.02tolk round

So these cushions have same area( first has a little bit less square area but you definitely can not see it)

So consumer does not need " to copy down your Tolk cut paramters, plug them into Diamcalc to get the diameter and thus surface area of the reference round. This is a backwards way of getting the surface area of the diamond of interest when it could be leasily listed as a line in the output." to understand which diamond is bigger if he has information about mass and Octonus spread. He does not need even DC. It is important advantages OctoNus SPread.
Any other questions?

 

[Garry H (Cut Nut)]

So CCL, Karl and Dave, does it make sense now?

As I have said before - Leonid and I implimented Spread into the In-House diamond listings many years ago. It has never been queried before to my knowledge. And it has surely assisted many thousands of buyers.

 

[Serg]

Date: 4/14/2010 2:29:07 AM
Author: Garry H (Cut Nut)
So CCL, Karl and Dave, does it make sense now?


As I have said before - Leonid and I implimented Spread into the In-House diamond listings many years ago. It has never been queried before to my knowledge. And it has surely assisted many thousands of buyers.

Garry, May be you need change spread unit system from % to ct. In such case consumer can easy compare any two diamonds without complex calculation.
DC uses both unit system for spread in same time

 

[Garry H (Cut Nut)]

Date: 4/14/2010 2:52:37 AM
Author: Serg

Date: 4/14/2010 2:29:07 AM
Author: Garry H (Cut Nut)
So CCL, Karl and Dave, does it make sense now?


As I have said before - Leonid and I implimented Spread into the In-House diamond listings many years ago. It has never been queried before to my knowledge. And it has surely assisted many thousands of buyers.

Garry, May be you need change spread unit system from % to ct. In such case consumer can easy compare any two diamonds without complex calculation.
DC uses both unit system for spread in same time

Dear Sergey,
I would be happy to do that, but remember these calculations are done for straight sided and round stones only on Pricescope. They are not from DiamCalc scanned data (which would be better).
Is the ''ct'' calculation still able to be done?
I suppose it is, but it has been a long day and my brain is dead.

 

[oldminer]

I know that Sergey's method is sensible to a very learned person who is into math and science. It probably has been useful to those who took the time to understand it as it is posted in the Pricescope listings in a rather easy to use format. To me, the way it is calculated seems rather complex and obtuse, but I have a less sophisticated approach in understanding yet it does work for me. However, the suggestion of simply putting the square mm of the girdle plane of any outline makes it clear which diamond looks larger than another similar diamond. That's so very simple and what we have in use, while totally correct, is far more deep and complicated. Sometimes consumers want simple, honest results rather than yet another layer of complexity requiring even more learning. Yes, the square mm of the girdle plane is not the sought after definition of "Absolute Spread" in the correct way Sergey has provided it, but the most useful component, the Comparative Simple Spread of similar weight diamonds would be a very welcomed addition.

 

[Serg]

Date: 4/14/2010 9:18:36 AM
Author: oldminer
I know that Sergey's method is sensible to a very learned person who is into math and science. It probably has been useful to those who took the time to understand it as it is posted in the Pricescope listings in a rather easy to use format. To me, the way it is calculated seems rather complex and obtuse, but I have a less sophisticated approach in understanding yet it does work for me. However, the suggestion of simply putting the square mm of the girdle plane of any outline makes it clear which diamond looks larger than another similar diamond. That's so very simple and what we have in use, while totally correct, is far more deep and complicated. Sometimes consumers want simple, honest results rather than yet another layer of complexity requiring even more learning. Yes, the square mm of the girdle plane is not the sought after definition of 'Absolute Spread' in the correct way Sergey has provided it, but the most useful component, the Comparative Simple Spread of similar weight diamonds would be a very welcomed addition.

Dave,

re:To me, the way it is calculated seems rather complex and obtuse

Please clarify what is complex in below method to compare two diamonds


DATA:
first diamond has mass 1.05ct and spread -0.03 ct
Second diamond has mass 1.02ct and spread 0.01ct

Consumer Needs :

1) Sum mass and spread for each diamond
2) Compare results

1.05ct -0.03ct=1.02ct
1.02ct+0.01ct=1.03ct
1.03 is bigger the 1.02, it means what second diamond is bigger.

What is complex here for anybody who can sum two numbers?

and why this method is Obtuse??

 

[ChunkyCushionLover]

Date: 4/14/2010 9:42:11 AM
Author: Serg

Date: 4/14/2010 9:18:36 AM
Author: oldminer
I know that Sergey''s method is sensible to a very learned person who is into math and science. It probably has been useful to those who took the time to understand it as it is posted in the Pricescope listings in a rather easy to use format. To me, the way it is calculated seems rather complex and obtuse, but I have a less sophisticated approach in understanding yet it does work for me. However, the suggestion of simply putting the square mm of the girdle plane of any outline makes it clear which diamond looks larger than another similar diamond. That''s so very simple and what we have in use, while totally correct, is far more deep and complicated. Sometimes consumers want simple, honest results rather than yet another layer of complexity requiring even more learning. Yes, the square mm of the girdle plane is not the sought after definition of ''Absolute Spread'' in the correct way Sergey has provided it, but the most useful component, the Comparative Simple Spread of similar weight diamonds would be a very welcomed addition.

Dave,

re:To me, the way it is calculated seems rather complex and obtuse

Please clarify what is complex in below method to compare two diamonds


DATA:
first diamond has mass 1.05ct and spread -0.03 ct
Second diamond has mass 1.02ct and spread 0.01ct

Consumer Needs :

1) Sum mass and spread for each diamond
2) Compare results

1.05ct -0.03ct=1.02ct
1.02ct+0.01ct=1.03ct
1.03 is bigger the 1.02, it means what second diamond is bigger.

What is complex here for anybody who can sum two numbers?

and why this method is Obtuse??

If the Octonus spread in carats not percentage always brings the final result equating the surface area of that diamond to an ideal tolk round with the same surface area than that is fine it removes the problem with percentages.
It might even be better to put (-0.03ct) 1.02Ct in the spread column and explain that this diamond has the same faceup surface area as a Tolk Round weighing 1.02 Carats.

But one should also give the surface area in mm squared in a second column it will help make things more clear when a consumer looks at a list of diamonds in understanding how spread translates to surface area.
Further you should explain clearly in a legend what both of the terms mean.

Also I would hope the template for the reference ideal tolk round is a default loadable one in Diamcalc so one could easily get the diameter of any weight reference round by changing Carat Weight.

 

[ChunkyCushionLover]

Date: 4/14/2010 2:29:07 AM
Author: Garry H (Cut Nut)
So CCL, Karl and Dave, does it make sense now?

As I have said before - Leonid and I implimented Spread into the In-House diamond listings many years ago. It has never been queried before to my knowledge. And it has surely assisted many thousands of buyers.

I don''t like percentage in the listing would prefer carat weight. I also don''t know where the legend is for this column. As done currently the consumer can guess what it means or its open to interpretation. That should be changed.

 

[Serg]

Date: 4/14/2010 11:04:08 AM
Author: ChunkyCushionLover

Date: 4/14/2010 9:42:11 AM

Author: Serg

Date: 4/14/2010 9:18:36 AM

Author: oldminer

I know that Sergey''s method is sensible to a very learned person who is into math and science. It probably has been useful to those who took the time to understand it as it is posted in the Pricescope listings in a rather easy to use format. To me, the way it is calculated seems rather complex and obtuse, but I have a less sophisticated approach in understanding yet it does work for me. However, the suggestion of simply putting the square mm of the girdle plane of any outline makes it clear which diamond looks larger than another similar diamond. That''s so very simple and what we have in use, while totally correct, is far more deep and complicated. Sometimes consumers want simple, honest results rather than yet another layer of complexity requiring even more learning. Yes, the square mm of the girdle plane is not the sought after definition of ''Absolute Spread'' in the correct way Sergey has provided it, but the most useful component, the Comparative Simple Spread of similar weight diamonds would be a very welcomed addition.

Dave,


re:To me, the way it is calculated seems rather complex and obtuse


Please clarify what is complex in below method to compare two diamonds



DATA:

first diamond has mass 1.05ct and spread -0.03 ct

Second diamond has mass 1.02ct and spread 0.01ct


Consumer Needs :


1) Sum mass and spread for each diamond

2) Compare results


1.05ct -0.03ct=1.02ct

1.02ct+0.01ct=1.03ct

1.03 is bigger the 1.02, it means what second diamond is bigger.


What is complex here for anybody who can sum two numbers?


and why this method is Obtuse??

If the Octonus spread in carats not percentage always brings the final result equating the surface area of that diamond to an ideal tolk round with the same surface area than that is fine it removes the problem with percentages.

It might even be better to put (-0.03ct) 1.02Ct in the spread column and explain that this diamond has the same faceup surface area as a Tolk Round weighing 1.02 Carats.


But one should also give the surface area in mm squared in a second column it will help make things more clear when a consumer looks at a list of diamonds in understanding how spread translates to surface area.

Further you should explain clearly in a legend what both of the terms mean.


Also I would hope the template for the reference ideal tolk round is a default loadable one in Diamcalc so one could easily get the diameter of any weight reference round by changing Carat Weight.

re:he Octonus spread in carats not percentage always brings the final result equating the surface area of that diamond to an ideal tolk round with the same surface area than that is fine it removes the problem with percentages.

CCL, Diamcalc gives information about spread in % and in carats in same time since 2002( last 8 years)
You can easy see it on Screenshots had been published by me in this topic. Just check my first post in this page

Do you see it now?

 

[Serg]

re:Also I would hope the template for the reference ideal tolk round is a default loadable one in Diamcalc so one could easily get the diameter of any weight reference round by changing Carat Weight.



It had been done more than 10 years ago in Diamcalc1.2

http://www.octonus.com/oct/products/3dcalc/standard/historyarchive.phtml

 

[ChunkyCushionLover]

Date: 4/14/2010 11:09:47 AM
Author: ChunkyCushionLover

Date: 4/14/2010 2:29:07 AM
Author: Garry H (Cut Nut)
So CCL, Karl and Dave, does it make sense now?

As I have said before - Leonid and I implimented Spread into the In-House diamond listings many years ago. It has never been queried before to my knowledge. And it has surely assisted many thousands of buyers.

I don't like percentage in the listing would prefer carat weight. I also don't know where the legend is for this column. As done currently the consumer can guess what it means or its open to interpretation. That should be changed.

To show you how confusing the current tables are here is an example, Top is a princess with 0.9 Ct and -22% spread.
What it means is -0.16 Ct or it has the same surface area as a 0.74Ct ideal tolk round. (0.74*1.22 = 0.9)

I would have preferred spread to be -18% and to be calculated as a function of the current weight (0.16/0.9). But either way carat weight is much better than percentage.

Both have the same surface area (with rounding). It would be much simpler to see the equivalency of the two if the surface area in mm squared was listed as well.

 

[Serg]

Date: 4/14/2010 11:42:44 AM
Author: ChunkyCushionLover

Date: 4/14/2010 11:09:47 AM

Author: ChunkyCushionLover

Date: 4/14/2010 2:29:07 AM

Author: Garry H (Cut Nut)

So CCL, Karl and Dave, does it make sense now?


As I have said before - Leonid and I implimented Spread into the In-House diamond listings many years ago. It has never been queried before to my knowledge. And it has surely assisted many thousands of buyers.

I don''t like percentage in the listing would prefer carat weight. I also don''t know where the legend is for this column. As done currently the consumer can guess what it means or its open to interpretation. That should be changed.

To show you how confusing the current tables are here is an example, Top is a princess with 0.9 Ct and -22% spread.

What it means is -0.16 Ct or it has the same surface area as a 0.74Ct ideal tolk round. (0.74*1.22 = 0.9)


I would have preferred spread to be -18% and to be calculated as a function of the current weight (0.16/0.9). But either way carat weight is much better than percentage.


Both have the same surface area (with rounding). It would be much simpler to see the equivalency of the two if the surface area in mm squared was listed as well.

% should be from reference diamond.

take two diamonds ( in current % system from reference diamond)

-20% spread and +20% spread
0.8 ct ( -0.20ct) and 1.2 ct( 0.20ct)
in both cases 20% means same 0.2ct

But in your system same +/- 0.2ct will -25% and 17%
I think it is more confusing ( even if it is more easy for calculations)

Because % from reference system is not easy for calculations, Diamcalc gives Spread in Carats and in %( from reference diamond) In Same Time

 

[oldminer]

I don''t want to be argumentative or offensive to anyone. It seems the method Sergey suggests we continue using is simple enough for him to explain and use, but it does seem far more complex in what it attempts to explain to a shopper than what the shopper actually may want to know. Maybe it tells them exactly what they need to know, but they may simply not be able to understand what they are being told.

Giving them square mm area is so simple that no explanation is required. Sergery''s method is useful for comparison of any two or more diamonds and tells something about the cut of each individual diamond. The simpler data I think folks would tend to want is for comparison of like stones only although they could be of any shapes, or any weight. It would not tell them which is more spread if they are not similar diamonds, but it would always tell them in the easiest terms which one was larger in visual size.....

 

[ChunkyCushionLover]

Date: 4/14/2010 1:05:45 PM
Author: oldminer

I don''t want to be argumentative or offensive to anyone. It seems the method Sergey suggests we continue using is simple enough for him to explain and use, but it does seem far more complex in what it attempts to explain to a shopper than what the shopper actually may want to know. Maybe it tells them exactly what they need to know, but they may simply not be able to understand what they are being told.

Giving them square mm area is so simple that no explanation is required. Sergery''s method is useful for comparison of any two or more diamonds and tells something about the cut of each individual diamond. The simpler data I think folks would tend to want is for comparison of like stones only although they could be of any shapes, or any weight. It would not tell them which is more spread if they are not similar diamonds, but it would always tell them in the easiest terms which one was larger in visual size.....

I''ve suggested listing both(spread in carat weight and surface area in mm squared) with the appropriate legend for both, which should satisfy all parties. The information itself is not misleading it is the application that may be and providing both would allow less room for interpretation.

 

[Serg]

Date: 4/14/2010 1:05:45 PM
Author: oldminer

I don''t want to be argumentative or offensive to anyone. It seems the method Sergey suggests we continue using is simple enough for him to explain and use, but it does seem far more complex in what it attempts to explain to a shopper than what the shopper actually may want to know. Maybe it tells them exactly what they need to know, but they may simply not be able to understand what they are being told.

Giving them square mm area is so simple that no explanation is required. Sergery''s method is useful for comparison of any two or more diamonds and tells something about the cut of each individual diamond. The simpler data I think folks would tend to want is for comparison of like stones only although they could be of any shapes, or any weight. It would not tell them which is more spread if they are not similar diamonds, but it would always tell them in the easiest terms which one was larger in visual size.....

Dave,
Yes we need avoid discussion on religion and philosophical issues . Choice between most simplest approach and correct approach is religion question . Both these approaches create mistakes in Business . I do not know which approach creates more mistakes .

we are in different camps here. I respect and understand your approach but I will not joint your camp .

 

[oldminer]

I do believe we both agree in the overall and have shown may readers why Depth is NOT the opposite of Spread in fancy shape diamonds. This was the basic subject of this thread and as many long threads do, it changed. Clearly less or shallow Depth is NOT ALWAYS the opposite of Spread. Weight can be increased or decreased without changing the depth of most any kind of diamond. The amount of bulge added or taken away from the faceting design can alter the visual size without regard to changes in depth.

The DiamCalc approach advises people of the efficient use of the material for visual size regardless of the carat weight allowing comparisons of any diamond, any shape to the theoretical efficient cutting of a Tolkowsky Ideal round. A consumer can defintely make use of this once they grasp the concepts involved. It is a pure mathmatical approach to the subject which has no error in it. I would not want to explain it to a client, but once I grasped it, it did make sense to me. My objection is purely on the subjective level of years of knowing what consumers want to understand and in a way that they need not be technically oriented or fluent in the language of mathmatics. My approach is "seat of the pants" and would not work well on stones which don''t weigh just about the same although one could compare any groups of shapes of similar weight to understand readily which diamond(s) look larger than another. You just don''t have to be sophisticated to understand my desired result and it is not a perfect tool like Sergey''s. But, in the real world, not the mathmatician''s world, my approach makes common sense in knowing the needs of the consumer-shopper.

Spread is a general term which can and does mean different things to different people, including diamond experts. I think spread refers to how much visual size one gets from the carat weight of a diamond COMPARED to other diamonds of similar weight. The largest looking one of a similar set becomes the most spread and the smallest looking is the least spread. Obviously, there is a camp which seeks to make spread a tool for understanding an individual diamond compared to an Ideal standard round cut. Of course, this works just fine and there is no reason to challenge it for correctness. I do think it an approach which answers a question rarely asked by anyone except maybe a diamond cutter.

Since Pricescope is truly consumer oriented, it may be a good thing to consider adding the square mm visual number somewhere so people can make quick comparisons during stone searches Since all diamonds in searches group initially by exact carat weight, they are already in the proper order for square mm comparison.

Sergey and I are going to go camping yet. We will just have to drink sufficient vodka to dissolve our differences..........

 

[Serg]

Dave ,
Sorry I am not in Vodka camp. Never even try
I hope you are in Vine camp too

 

[Garry H (Cut Nut)]

Date: 4/14/2010 4:12:44 PM
Author: oldminer
I do believe we both agree in the overall and have shown may readers why Depth is NOT the opposite of Spread in fancy shape diamonds. This was the basic subject of this thread and as many long threads do, it changed. Clearly less or shallow Depth is NOT ALWAYS the opposite of Spread. Weight can be increased or decreased without changing the depth of most any kind of diamond. The amount of bulge added or taken away from the faceting design can alter the visual size without regard to changes in depth.

The DiamCalc approach advises people of the efficient use of the material for visual size regardless of the carat weight allowing comparisons of any diamond, any shape to the theoretical efficient cutting of a Tolkowsky Ideal round. A consumer can defintely make use of this once they grasp the concepts involved. It is a pure mathmatical approach to the subject which has no error in it. I would not want to explain it to a client, but once I grasped it, it did make sense to me. My objection is purely on the subjective level of years of knowing what consumers want to understand and in a way that they need not be technically oriented or fluent in the language of mathmatics. My approach is ''seat of the pants'' and would not work well on stones which don''t weigh just about the same although one could compare any groups of shapes of similar weight to understand readily which diamond(s) look larger than another. You just don''t have to be sophisticated to understand my desired result and it is not a perfect tool like Sergey''s. But, in the real world, not the mathmatician''s world, my approach makes common sense in knowing the needs of the consumer-shopper.

Spread is a general term which can and does mean different things to different people, including diamond experts. I think spread refers to how much visual size one gets from the carat weight of a diamond COMPARED to other diamonds of similar weight. The largest looking one of a similar set becomes the most spread and the smallest looking is the least spread. Obviously, there is a camp which seeks to make spread a tool for understanding an individual diamond compared to an Ideal standard round cut. Of course, this works just fine and there is no reason to challenge it for correctness. I do think it an approach which answers a question rarely asked by anyone except maybe a diamond cutter.

Since Pricescope is truly consumer oriented, it may be a good thing to consider adding the square mm visual number somewhere so people can make quick comparisons during stone searches Since all diamonds in searches group initially by exact carat weight, they are already in the proper order for square mm comparison.

Sergey and I are going to go camping yet. We will just have to drink sufficient vodka to dissolve our differences..........

I often show customers who initially think they want a solitaire an option in their price range a 3 stone ring. About 1/3rd go with the 3 stone because they get a lot more square mm''s for their money.

Here is a little princess cut example:
a 6mm center with two 5mm stoenes wither side = 5x5=25mmsq and 6x6=36 for a total of 86mmsq. Say $15k
The same 86mm sq sized solitaire is 5ct and $144k.