Would an Ideal cut diamond always have better light performance than an excellent cut?

[gamerkonks]

Given two diamonds, eye-clean, comparable size, color, etc. will the higher graded cut, always have better light performance?
I guess that depending on the amount of brilliance / fire of each stone, at high cut grades, the better diamond could come down to personal preference?
Or is the higher graded cut always a better diamond?


*I understand 'Ideal' and 'Excellent' are IGI terms, but I mean for any diamonds where one is the highest grade, and the other is in the next grade down.

 

[munchee]

Ideal is what AGS use and Excellent is what GIA use. With AGS lab report you can see the aset, hence you can see if there is any leakage. While GIA 3ex itself has a very wide range, if your question is: “Can I get a better light performance from GIA 3ex than Ideal stone?” The answer is, yes you can, absolutely! But in order to get that, you need to know what are you looking, due to the super wide range GIA 3ex. Not all GIA 3ex has good light performance. You really need to find it, using Aset/Idealscope is the easiest to see leakage. In this forum you can buy it or you can make your own DIY scope to check if the diamond has any leakage.

If your questions is “is higher grade cut (ex/ideal) is better than Very good graded cut?” The answer I believe yes, Ex/Ideal diamond will be better than a diamond that have Very Good cut.

 

[flyingpig]

Symmetry, polish, depth and girdle thickness, culet size, digging/painting are also considered determining cut grade. There are plenty of VG and Good cut diamonds that perform better than some steep and deep Ex cut diamonds.
So my answer is No.

 

[munchee]

Symmetry, polish, depth and girdle thickness, culet size digging/painting are also considered determining cut grade. There are plenty of VG and Good cut diamonds that perform better than some steep and deep Ex cut diamond.
So my answer is No.

Trust his answer, not mine

 

[headlight]

There are so many factors; we could give a blanket statement, but truly each stone needs to be judged on its own merit, and it is not uncommon that the specific end user takes into account a number of factors and gives consideration to all when making a decision best for them.

 

[Karl_K]

Symmetry, polish, depth and girdle thickness, culet size, digging/painting are also considered determining cut grade. There are plenty of VG and Good cut diamonds that perform better than some steep and deep Ex cut diamonds.
So my answer is No.

My answer is no also but I would add it also depends on what the diamond is being used for as most of the grading systems are ring use biased and there are combos that are not great in a ring but rock in earrings and pendants.

 

[munchee]

This is interesting, if one get Excellent and one get Very good, and the VG is actually is better, why the Excellent graded Ex? Does this also apply in AGS0 and AGS1 too? That there’s a chance AGS1 is better than AGS0 too? @flyingpig @Karl_K

 

[Karl_K]

This is interesting, if one get Excellent and one get Very good, and the VG is actually is better, why the Excellent graded Ex? Does this also apply in AGS0 and AGS1 too? That there’s a chance AGS1 is better than AGS0 too? @flyingpig @Karl_K

You have to draw a line somplace when designing a grading system and there will always be exceptions.
yes to both vg could be better than some ex and same ags1 and ags0