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 F♯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♭.
B♭♭ and D♭♭ are double flats, and they have to be: every letter from G♭ upwards is used once, so the b3 cannot be written any other way.