ChunkyCushionLover
Ideal_Rock
- Joined
- Jun 21, 2009
- Messages
- 2,463
Lorelei,
Garry has said "he will not use numbers when buying a fancy diamond from a distance and prefers images and video."
Jon has said "knowing crown height alone without seeing how it works in synergy with the pavilion angles, lower half angles and lower half length is moot information and incomplete for the overall picture."
I think it is even more unreasonable to arbitrarily set a value for cushions of a crown height of at least 10% which you have done several times here are two examples:
https://www.pricescope.com/community/threads/cushion-experts-help-pls.127687/
https://www.pricescope.com/community/threads/help-with-cushion.129188/
Requesting this information and your comments on a minnimum crown height achieve the following undesireable consequences:
i) limits the vendors the customer will consider if only a handful can or are willing provide sarin information
ii) may be used by novice customers for selection and rejection even if they don't understand what this information is used for or your intention when asking for this information
iii) may be used by novice consumers along with other cushion stats to incorrectly guess at light performance
While we all may agree that the CH% in of itself provide very little towards understanding a stones optics (I would much rather know the average crown and pavillion angles along with the crown height) it does have a much more dramatic impact on the number of vendors a customer can consider if they want to readily receive this information. To my knowledge there are only two PS vendors and a handful of other vendors online who provide sarin information on cushions. GOG has this information for about half of their cushions and WF for only their premium selected cushions. For any other vendor or any other virtual stone providing this information is a burden at the very least for the vendor and it may exclude them from servicing a customer who fails to understand the lack of importance of knowing this information.
I would have rathered a more in depth discussion from the tradesmembers here in this thread with particular focus on reasonable crown heights and crown/pavillion angle combinations to provide theoretical support for the considerable empirical evidence I have collected for but for now all I see is not much beyond "leave it to the experts".
The chunky faceted 8 main antique stones most often sought after by Pricescopers and commonly sourced by GOG and ERD over the years have many of the same following characteristics see fine examples below. They all have crown heights almost double or more your 10% arbitrary value which is far too shallow to obtain the approximately 40 crown angle required for the biggest and boldest chunky virtual facets.
Examples:
AVCs
http://www.goodoldgold.com/diamond/6546/ (Crown Height 22.4% Crown Angle 40.4 Pavillion Angle 38.7 Depth 65% Table 48%)
http://www.goodoldgold.com/diamond/6929/ (Crown Height 22.5% Crown Angle 41 Pavillion Angle 40.4 Depth 70% Table 54%)
Non AVC Antique Cushions
http://www.goodoldgold.com/diamond/6974/ (CH 19% CA 46.5 PA 37.7 Depth 63% Table 58%) ( Steep Crown/Shallow Pavillion Combination cause some obstruction under the table here but still really nice overall)
http://www.goodoldgold.com/diamond/4899/ (CH 19% CA41.7 PA 38.7 Depth 64.9% Table 60%) ( Slight mismatch of CA/PA could be the cause of minimal leakage on the outside of the table but still nice overalll)
Even modern faceted cushions with larger tables, more moderate crowns and those that favour brightness over fire require reasonably tall crowns. A few well cut examples of these are shown below:
Modern Faceted Cushions:
4 main
http://www.goodoldgold.com/diamond/6922/ (CH 15% CA 38.6 PA 38.2 Table 67% Depth 72%)
8 main thin
http://www.goodoldgold.com/diamond/4105/ (CH 18% CA 39.3 PA 37.4 Table 56% Depth 65%)
http://www.goodoldgold.com/diamond/6979 (CH 17% CA 37.4 PA 42.2 Table 56.5% Depth 68.1%)
Cushette
http://www.goodoldgold.com/diamond/4258/http://www.goodoldgold.com/diamond/3458/http://www.goodoldgold.com/diamond/4270/ (CH 13% CA 38.2 PA 59.8 Table 68% Depth 71.3%)
It is quite trivial for anyone interested in diamond optics to answer the question whether or not they would like to know the crown height or if it would be "nice" to have this information. The answer would always be yes. However the practical cost and limited use of this information far outweighs its value especially if you don't even know the facet structure.
You can continue your pragmatic approach to evaluating cushions, although I'm not sure that is quite appropriate or expected for someone with "Prosumer" in their signature line but maybe just maybe in future you will consider more carefully why you are asking for this number, what range you are expecting, and what you will do with it once received.
CCl
Garry has said "he will not use numbers when buying a fancy diamond from a distance and prefers images and video."
Jon has said "knowing crown height alone without seeing how it works in synergy with the pavilion angles, lower half angles and lower half length is moot information and incomplete for the overall picture."
I think it is even more unreasonable to arbitrarily set a value for cushions of a crown height of at least 10% which you have done several times here are two examples:
https://www.pricescope.com/community/threads/cushion-experts-help-pls.127687/
https://www.pricescope.com/community/threads/help-with-cushion.129188/
Requesting this information and your comments on a minnimum crown height achieve the following undesireable consequences:
i) limits the vendors the customer will consider if only a handful can or are willing provide sarin information
ii) may be used by novice customers for selection and rejection even if they don't understand what this information is used for or your intention when asking for this information
iii) may be used by novice consumers along with other cushion stats to incorrectly guess at light performance
While we all may agree that the CH% in of itself provide very little towards understanding a stones optics (I would much rather know the average crown and pavillion angles along with the crown height) it does have a much more dramatic impact on the number of vendors a customer can consider if they want to readily receive this information. To my knowledge there are only two PS vendors and a handful of other vendors online who provide sarin information on cushions. GOG has this information for about half of their cushions and WF for only their premium selected cushions. For any other vendor or any other virtual stone providing this information is a burden at the very least for the vendor and it may exclude them from servicing a customer who fails to understand the lack of importance of knowing this information.
I would have rathered a more in depth discussion from the tradesmembers here in this thread with particular focus on reasonable crown heights and crown/pavillion angle combinations to provide theoretical support for the considerable empirical evidence I have collected for but for now all I see is not much beyond "leave it to the experts".
The chunky faceted 8 main antique stones most often sought after by Pricescopers and commonly sourced by GOG and ERD over the years have many of the same following characteristics see fine examples below. They all have crown heights almost double or more your 10% arbitrary value which is far too shallow to obtain the approximately 40 crown angle required for the biggest and boldest chunky virtual facets.
Examples:
AVCs
http://www.goodoldgold.com/diamond/6546/ (Crown Height 22.4% Crown Angle 40.4 Pavillion Angle 38.7 Depth 65% Table 48%)
http://www.goodoldgold.com/diamond/6929/ (Crown Height 22.5% Crown Angle 41 Pavillion Angle 40.4 Depth 70% Table 54%)
Non AVC Antique Cushions
http://www.goodoldgold.com/diamond/6974/ (CH 19% CA 46.5 PA 37.7 Depth 63% Table 58%) ( Steep Crown/Shallow Pavillion Combination cause some obstruction under the table here but still really nice overall)
http://www.goodoldgold.com/diamond/4899/ (CH 19% CA41.7 PA 38.7 Depth 64.9% Table 60%) ( Slight mismatch of CA/PA could be the cause of minimal leakage on the outside of the table but still nice overalll)
Even modern faceted cushions with larger tables, more moderate crowns and those that favour brightness over fire require reasonably tall crowns. A few well cut examples of these are shown below:
Modern Faceted Cushions:
4 main
http://www.goodoldgold.com/diamond/6922/ (CH 15% CA 38.6 PA 38.2 Table 67% Depth 72%)
8 main thin
http://www.goodoldgold.com/diamond/4105/ (CH 18% CA 39.3 PA 37.4 Table 56% Depth 65%)
http://www.goodoldgold.com/diamond/6979 (CH 17% CA 37.4 PA 42.2 Table 56.5% Depth 68.1%)
Cushette
http://www.goodoldgold.com/diamond/4258/http://www.goodoldgold.com/diamond/3458/http://www.goodoldgold.com/diamond/4270/ (CH 13% CA 38.2 PA 59.8 Table 68% Depth 71.3%)
It is quite trivial for anyone interested in diamond optics to answer the question whether or not they would like to know the crown height or if it would be "nice" to have this information. The answer would always be yes. However the practical cost and limited use of this information far outweighs its value especially if you don't even know the facet structure.
You can continue your pragmatic approach to evaluating cushions, although I'm not sure that is quite appropriate or expected for someone with "Prosumer" in their signature line but maybe just maybe in future you will consider more carefully why you are asking for this number, what range you are expecting, and what you will do with it once received.
CCl
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