Fully Diminished Chords There are only really 3 diminished chords. Because they are built up of only minor thirds, each fully diminshed chord is also 3 other diminished chord.
E AD G You can also use your 3rd finger instead of your pinky here - Whatever is most comfortable for you
For example, this F# diminished 7th chord shares the same notes as an A diminished 7th chord, as well as the C diminished 7th chord and the Eb diminished 7th chord. Whatever note is on the bottom of a fully diminished chord is the root of the chord at that time. In this example, an F# is the lowest note in this shape (Fret 2 on the E string) Therefore, this is an F# diminished 7th chord.