guitar chord
F♯m7♭5
A diminished triad with a minor seventh rather than a diminished one — half diminished, and not the same chord as dim7.
Written the other way round it is G♭m7♭5 — the same twelve keys on a piano, a different piece of notation.
Every fingering that fits a hand
202210
moderate
204210
moderate
202550
moderate
204550
moderate
20221x
moderate
What is true of it
F♯m7♭5 is F♯, A, C and E — 1, b3, b5 and b7 counted from F♯.
These are also the notes of Am6/F♯. Which name is right depends on what is underneath and what came before — the notes alone do not decide.
The easiest of the 5 fingerings below is 202210: 4 fingers, held at the 1st fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
Where its notes are on the neck
The brass dots are F♯, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
F♯m7♭5/A
504550
F♯m7♭5/C
x34210
F♯m7♭5/E
004550
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.