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How do slight changes in proportions affect a stone's performance?

Linny

Rough_Rock
Joined
Mar 7, 2019
Messages
57
The top is my current stone:

Table 56.7, crown angle 34.6. Pavillion 40.9, LGF 78

verses this one, for example:

Table 55, crown angle 34.3, Pavillion 40.7, LGF 76

How do these changes in proportions affect the stone's performance? I.e. fatter arrows, etc.... I apologize if this is a rudimentary question!
 
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flyingpig

Ideal_Rock
Premium
Joined
Nov 7, 2015
Messages
2,245
The new one has a smaller table, shorter LGF, and shallower pavilion. All of these will make the arrows longer and fatter and the table reflection smaller.

One is not necessarily better than the other. But will there be noticeable difference? I say yes. On side-by-side comparison, you will know which is which.
 

AV_

Ideal_Rock
Joined
Aug 5, 2018
Messages
3,849
I suspect that the difference between those numbers are smaller than the measurements are precise, so they are not telling me that there is any difference between the stones.

-

The quetsion remains: if a diamond may loose its brilliance by a .1 or .2 or .3 degrees change of a main angle (in theory, or by recut - if such can be done); I can't think of what you'd have to start with, but remember that the work for the HCA brought up the oddities in theory, & the possibility was ever far off the Ideal beaten track; the good numbers can also stand variations.



@Garry H (Cut Nut)
 
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Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,305
The new one has a smaller table, shorter LGF, and shallower pavilion. All of these will make the arrows longer and fatter and the table reflection smaller.

One is not necessarily better than the other. But will there be noticeable difference? I say yes. On side-by-side comparison, you will know which is which.
But if they are for earrings or eithr side of another diamond with some slope you will never notice. Both are nice proportions
 

Gemly

Rough_Rock
Joined
May 29, 2020
Messages
80
But if they are for earrings or eithr side of another diamond with some slope you will never notice. Both are nice proportions
Hi Gary,
I’m curious, would the example with the table 55, crown angle 34.3, Pavillion 40.7, LGF 76 end up experiencing any head obstruction issues? Would this be an equal balance of brilliance and fire?
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,305
Hi Gary,
I’m curious, would the example with the table 55, crown angle 34.3, Pavillion 40.7, LGF 76 end up experiencing any head obstruction issues? Would this be an equal balance of brilliance and fire?
Yes if you have a big head, or huge hat and are looking at the diamond from less than 6 inches 15cm.
 

Gemly

Rough_Rock
Joined
May 29, 2020
Messages
80
Yes if you have a big head, or huge hat and are looking at the diamond from less than 6 inches 15cm.

If you could see the size of my head you’d know why I’m asking this question!!:lol:


But in all seriousness, would the table 55, crown angle 34.3, Pavillion 40.7, LGF 76 end up having an equal balance of fire and brilliance? Would depth affect this (say a depth of 61.8 )Or would it lean more one way or the other in terms of fire or brilliance? Thanks Gary!! Love hearing your perspective!!
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,305
If you could see the size of my head you’d know why I’m asking this question!!:lol:


But in all seriousness, would the table 55, crown angle 34.3, Pavillion 40.7, LGF 76 end up having an equal balance of fire and brilliance? Would depth affect this (say a depth of 61.8 )Or would it lean more one way or the other in terms of fire or brilliance? Thanks Gary!! Love hearing your perspective!!
Nothing to do with depth - almost entirely about pavilion depth.
If the pavilion gets close to 4 your head will obstruct lots of light unless you wear a headlight between your eyes it will look dark
 

Gemly

Rough_Rock
Joined
May 29, 2020
Messages
80
Nothing to do with depth - almost entirely about pavilion depth.
If the pavilion gets close to 4 your head will obstruct lots of light unless you wear a headlight between your eyes it will look dark
That makes sense, thank you so much!! Last question on this subject...promise! ....Would the 40.7 PA 34.3 CA with a 55 table (15.5%) end up leaning more towards brilliance than fire...or more fire than brilliance...or would it be completely balanced in terms of fire and brilliance ?
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,305
That makes sense, thank you so much!! Last question on this subject...promise! ....Would the 40.7 PA 34.3 CA with a 55 table (15.5%) end up leaning more towards brilliance than fire...or more fire than brilliance...or would it be completely balanced in terms of fire and brilliance ?
Balanced with maybe a teensy weensy bit more fire because the small table
 
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