Yes, these seem to be my thoughts, but I am wondering if it was the cut as well (the difference in sizes weren''t as immense as you are describing).
I recently purchased an ideal cut princess from BN, and it sparkles a ton, kinda like a sea of tiny little diamonds inside. I went to look for a band at Jared the other day, and out of curiosity, asked to see the LEO diamond (I had been reading a lot about them, and decided against it). Of course, the guy brings out a larger diamond than mine (1.02 ct vs. 1.50 ct in leo). Everything else aside (mine was MUCH more colorless (E) and a VS1 vs. an S1), the sparkle seemed to be a little different, and I couldn''t decide which was better and if it was the cut or the size difference. The leo had less but seemingly "bigger" flashes of light, whereas mine has many many flashes of light, but a little "smaller." I can''t at this point decide which is better (Also, the leo stone was loose and mine was mounted, so maybe the loose stone let light in through the pavilion as well (artificial sparkle). I am now wanting to have ASET images taken to ease my worry about whether my stone is leaking more light than I had hoped...even though it does sparkle a lot (it is an ideal cut)...pretty much I am searching for the perfect diamond, which doesn''t exist...so I was just wondering if what I noticed being different in the diamonds could be explained by size differences...haha sorry for my babbling.