I am getting rapidly tired of this discussion. I have listened to the whole recorded output of Blind Blake enough to know the difference between a diminished chord and a triad which forms part of a dominant seventh.

A diminished chord is a chord comprising notes each separated from the next by an interval of three semitones. And it goes all the way up from low tonic to high tonic.

An augmented chord is a chord comprising notes each separated from the next by an interval of four semitones. And it goes all the way up from low tonic to high tonic.

That's it , period.

Murray