I climbed up the same route to Peak 12055. I knew you could reach Jasper from the Diamond Lake Route. Glad someone finally put it up!
Actually, the East Ridge is the one NW of Diamond Lake while 12055 is due south of the lake. Pt12055 is the root of the SE ridge (Jasper is more complicated than entirely necessary). I'd hoped to descend via the SE ridge to see how things looked over there, but my partner got sick above 12,500' and couldn't proceed.