Blue Nile Astor Princess Diamond - GemEx Certificate Useful or Not?

First of all I’d like to thank you for your knowledge & advice that you put into your website. So, basically I have narrowed down my choices between these two stones: Blue Nile Astor Princess diamond and Whiteflash A Cut Above Princess diamond. Which in your opinion is the better princess cut diamond?

This Astor TM diamond, 0.24 carat D color vs2 clarity has ideal proportions and a diamond grading report from GIA

0.24 Carat D-VS2 AstorPrincess Cut Diamond

Blue Nile Review: Really Good Place to Buy a Ring?

0.29 Carat H-VVS2 AstorPrincess Cut Diamond

This Astor TM diamond, 0.32 carat H color vs1 clarity has ideal proportions and a diamond grading report from GIA

0.32 Carat H-VS1 AstorPrincess Cut Diamond

1.31ct Blue Nile Astor Cushion Diamond Engagement Ring F VS2 GIA in Pl

James Allen vs Blue Nile - Which is Better in Comparison? (With Videos)

Certificate - evaanta

Astor Collection Diamonds by Blue Nile Review

Astor Cut Vs. Tiffany Choosing from the Best of the Best - Road to Glamour

This Astor TM diamond, 2.11 carat G color vvs1 clarity has ideal proportions and a diamond grading report from GIA

2.11 Carat G-VVS1 AstorPrincess Cut Diamond