It's such a shame that there isn't much on this beautiful butterfly. All that I could gather was this from Wikipedia:
The Emerald Swallowtail (Papilio palinurus) is a butterfly found primarily in South East Asia and is one of the very few green butterflies around. It is also referred to as Emerald Peacock or Green-banded Peacock Swallowtail.
Wikipedia also mentions that there are alot subspecies. This one in the photo is blue but it could very well be from the way the light is reflecting off of it's wings.
Of course there's also the possibility of it being:
1. One of the many subspecies
2. Has yet to turn green because it just emerged from the pupa
But what do I know? I'm just guessing here! :P