G# b5/C#
The G# b5 chord consists of the G# (Perfect unison), C (Major third) and D (Diminished fifth) notes, with C# as the bass note.

How to play the G# b5/C# chord
- Play C# as the lowest bass note in the left hand
- Find G# (Root) on the piano keyboard
- Add C (Major third) — 4 semitones above G#
- Add D (Diminished fifth) — 6 semitones above G#
- Press all 4 notes simultaneously to sound the G# b5/C# chord