Banjo Gdim chord (Open G)G diminished on the 5-string banjo: 5 3 2 5, and 3 more shapes

Frets, string 4 to string 1: 5 3 2 5 (from the 2nd fret)

1. String 4 (D): 5th fret, ring finger, G
2. String 3 (G): 3rd fret, middle finger, B♭
3. String 2 (B): 2nd fret, index finger, D♭
4. String 1 (D): 5th fret, little finger, G
5. String 5, the short g: open, G, in the chord

Sounds: G B♭ D♭ G  ·  Gdim is G, B♭, D♭ (1 · ♭3 · ♭5)

Found in: A♭ major (vii°), E♭ mixolydian (iii°), B♭ dorian (vi°), F minor (ii°)

The 5th string: the short g is the root of Gdim, so let it ring.

With a capo: on the 5th fret it’s 0 1 3 3 (frets counted from the capo), an open Ddim shape. Spike the 5th string at the 10th fret to keep it in tune with the capo.

Open G tuning: gDGBD, the short 5th string first, then strings 4 to 1.