G dim/G#
The G dim chord consists of the G (Perfect unison), A# (Minor third) and C# (Diminished fifth) notes, with G# as the bass note.

How to play the G dim/G# chord
- Play G# as the lowest bass note in the left hand
- Find G (Root) on the piano keyboard
- Add A# (Minor third) — 3 semitones above G
- Add C# (Diminished fifth) — 6 semitones above G
- Press all 4 notes simultaneously to sound the G dim/G# chord