Abjuration augments

Can someone please explain to me how you change the augments on Abjuration gear. I have chosen path D augments, but only get one type. I didn't want to keep leveling this one set of augments, when I want another set of path D augments. I tried Mezzotinting multiple times but seem to get same set of augments.

Thanks,

Ashel

Path D will always be the same for any given item. Like all augments, it varies from set to set, but type D also varies from piece to piece.