You do not assess light performance from that angle.
You are overanalysing. What does it look like face up?
This really puts my mind at ease, thank you!
I thought I might be, thank you. I like it but it isn't perfect, though I've been obsessing over diamonds for a year now so am thinking I just can't afford what I think is perfect - or it doesn't exist.
I hear ya, in reviewing ovals for almost a year, I never saw a single one in particular that blew me away in terms of brilliance or fire etc., I did see some really bad bow ties though. After having too many disappear as soon as I made up my mind to purchase them, I feel like I sort of "settled", but I'm very happy with my stone (coming around to the setting), I think the key is to stop comparing to other ones, as long as you find one that meets your expectations of how you want it to look, I think you'll find you'll be happy.
In regards to your original question though... if you are wearing it around the house, running errands, walking outside, that's how I would be judging if I'm happy with its light return. You may find that an oval is not the shape for you if your expectations are blinding light sparkle because I just don't think that exists with ovals, or at least it's very rare.
Hope this helps from another over analyzing, oval diamond obsessor
The photos at the beginning show a novel approach that a consumer created for their own use and communication with forum members. Maybe there is something here that demonstrates some useful information, but I don't think so. Light return measurements and tools such as ASET and IS depend on a fixed lighting environment. Even the best diamond cuts leak light in many directions that go unmeasured. The top view is of greatest importance and that's where light performance in diamonds is graded. The best of Ideal cuts set upside down would not be impressive to viewers.