I know this isn't exactly an original post, but I found the Milani Luminous blush by chance a couple of days ago at Beauty Base in Westfield, and so thought I may as well do the obligatory compare and contrast to Nars Orgasm.
Side by side 1 (and not helpful at all):
On first look, they are pretty damn similar. The Milani blush is a bit lighter and pinker in the pan, but not massively different at all. See:
I have to say, I'm not sure I get what all the fuss is about Orgasm. It is an undeniably pretty blush but I was expected to be wowed by it and to use it all the time and repurchase, blah blah blah, but I hardly ever reach for it and when I do, it's not that amazing. I like the Milano Luminous blush a lot, and would absolutely repurchase, but as a blush in its own right, not just as a dupe.