Very good cut grade, but HCA excellent?

[rook02]

I was wondering how a very good cut grade on the GIA certificate can have a HCA less than 2. Are they looking at different things?

 

[Christina...]

Yes they are different things. HCA is a predicter or light performance, it's possible to find a VG cut that will out perform a GIA EX cut. I was looking for specific proportions when I purchased my diamond and they happened to fall in AGS0 range but GIA VG and it scored 1 on HCA. What are the specs of the stone your considereing?