piano chord
G♯dim
G♯1B♭3D♭5
Two minor thirds stacked. The fifth is diminished, so it cannot be dropped without losing the chord.
Written the other way round it is A♭dim — the same twelve keys on a piano, a different piece of notation.
What is true of it
G♯dim is G♯, B and D — 1, b3 and b5 counted from G♯.