Root on A string
x-10-11-x-11-12
Gdim7 is the G diminished 7 chord. Its notes are G, B♭, D♭ and F♭. Stacked minor thirds. Its symmetrical sound makes it useful as a passing chord.
x-10-11-x-11-12
Numbers show frets from the low E string to the high e string; x means don't play that string.
Every G, B♭, D♭ and F♭ on the first 12 frets. The filled dots are the root, G. Build your own shape from any nearby group.
Other G chords
Other diminished 7 chords