G dim7
The G dim7 chord consists of the G (Perfect unison), A# (Minor third), C# (Diminished fifth) and E (Major sixth) notes.

How to play the G dim7 chord
- Find G (Root) on the piano keyboard
- Add A# (Minor third) — 3 semitones above G
- Add C# (Diminished fifth) — 6 semitones above G
- Add E (Major sixth) — 9 semitones above G
- Press all 4 notes simultaneously to sound the G dim7 chord