You can use the F# diminished chords from the key of G major in place of D dominant 7th chords if you want a harsher resolution to the G chord.
I cover the intervals and notes for each diminished chord and include some song examples that use F# dim and dim7 chords.
Try my 21 open F# diminished guitar chords to see if you like their sound: 13 from G major and the remaining 8 from various minor scales.
Six F# diminished chord types
There are a total of 6 commonly seen diminished chord types, though you will only see 3 of them in jazz pieces. Here are the 3 diminished chords that can be built from the G major scale:
dim triad: root note, minor 3rd, diminished 5th = R-m3-d5 = 1-♭3-♭5
Alternate symbol: o, for example, F#o
F# dim = F#-A-C
m7♭5 chord: root note, minor 3rd, diminished 5th, minor 7th = R-m3-d5-m7 = 1-♭3-♭5-♭7
Alternate symbol: ø7, for example, F#ø7
Chord equivalent = m6 on the ♭3
F#m7b5 = F#-A-C-E = Am6
m11♭5 chord: root note, minor 3rd, diminished 5th, minor 7th, perfect 4th/11th = R-m3-d5-P4 = 1-♭3-♭5-♭7-11
Chord equivalent = m6 add9 on the ♭3, 7sus ♭9 on the 4th
F#m11b5 = F#-A-C-E-B = Am6 add9 = B7sus ♭9
The strongest tendency for all 3 chords is to the I chord G major in whatever form it takes: G, G6. G6 add9, Gmaj7, etc. E minor would follow those chords nicely as well.
The next 3 diminished chords come from the G harmonic minor, A melodic minor, and the B♭ harmonic minor scales respectively. These are just for your reference. They can NOT be built from the major scale.
dim7 chord: root note, minor 3rd, diminished 5th, diminished 7th = R-m3-d5-d7 = 1-♭3-♭5-♭♭7
Alternate symbol: o7, for example, F#o7
Chord equivalent: equals a dim7 for every other chord tone
F# dim7 = F#-A-C-E♭ = A dim7, C dim7, E♭ dim7
Chord tendency: resolves up a semitone for each chord tone, F#dim7 resolves to G, A#\B♭, C#, and F major, and you can include the relative AND parallel minors of each of those keys as well.
F#m9♭5 chord: root note, minor 3rd, diminished 5th, minor 7th, major 2nd\9th = R-m3-d5-M2 = 1-♭3-♭5-9
Chord equivalent: equals a 7#5♭9 on the 9
F#m9♭5 = F#-A-C-E-G# = G#7#5♭9
Chord tendency: resolves best to G and C# but also to F# and C.
m-maj7♭5 chord: root note, minor 3rd, diminished 5th, major 7th = R-m3-d5-M7 = 1-♭3-♭5-7
F#m-maj7♭5 = F#-A-C-E#
Chord tendency: resolves to G and C# but also F# and A#\B♭.
21 Open F# diminished guitar chord shapes
Although this article is geared towards the 3 diminished chord types found in the key of G major, I’m including the dim7, m9♭5, and m-maj7♭5 chords as well. I might as well. Where else would I cover those chords?
If you would like to learn the closed chord voicings for all the diminished chord types, then take a look at my Diminished Triad article.
Here is a chord diagram of the symbols I use in my chord blocks:
Notes on the chord voicings:
F# dim triad: #1 is a little difficult but I like it and #2 is my favorite.
F#m7♭5: #’s 2, 3 & 6 are my favorites.
F#m11♭5: Even though #1 is difficult, it’s the most ominous of all these diminished chords, although #2 is spooky too – love them both.
F#dim7: They all sound good.
F#m9♭5: I only like #1.
F#m-maj7♭5: This is not a chord I use, but I like #2, especially since it is the bottom half of a 7#9 chord.
Songs that use an F# diminished chord
Here are some songs that use one of the guitar voicings found above:
Beatles: G♭dim in I’m Happy Just To Dance With You
Grateful Dead: F#dim7 in Ship of Fools
Simon & Garfunkel: F#dim in Bridge Over Troubled Water
Jerry Reed: F#dim7 in The Claw
Also look at my Diminished Chords article for example of other songs that use diminished chords, though not all in the key of F#.
I personally only occasionally use a dim, m7♭5 or dim7 chord in my songs, although I like the m11♭5 chord and I use the chord equivalent of the m9♭5 (7#5♭9). It’s interesting that a m-maj7♭5 chord is a full 7#9 chord without the root (F#m-maj♭5 = D7#9 no root).
If you like the easier to grab full diminished chord sound, then I’m sure you’ll find some F# voicings above that you’ll find useful in your songs. Check out the Wikipedia page on the diminished triad if you like these types of chords.