to the iris forum, Rebekah!!
I have researched true blue irises recently, because I am making a memorial bed to my grandmother, who loved all shades of blue. The only two, which people consistently report to bloom 'true blue' are Absolute Treasure and Dodger Blue, like Bonnie already mentioned. I am sure there are others, less well-known perhaps, which are also blue rather than purple, but these are the ones I have picked after reading through all the threads on blue irises I could find.
However, if you look into the smaller irises, you will find plenty of 'true blue' ones, especially among the 'dwarf's.
PS: I too have 'Alien Mist' and though it does look kind of soft blue from a distance, I agree with Bonnie that it has a distinct lilac hue to it:
