I have a serious love affair with shimmery blues. It's ridiculous. Someday I'll have to do a comparison of them all... But I'm about to move back to my parent's for a month while I play for a theatre this summer, so I probably won't have time for a couple months! Just don't let me forget. ;)
Today's shimmery blue is Milani Sail Away. It's freaking gorgeous. They released this and Beach Front in the same collection this spring, and I just died.
It's a perfect cornflower shade of blue with the most incredible silver shimmer. And the shimmer is not at all shy!
I think this is probably very similar to Sinful Colors Neptune. Unless you're like me and need every shimmery blue ever invented, you'd probably be fine with just one or the other.