Diminished Chords

The diminished chord is made up of four notes. When compared to the major scale they are:

1stb3rdb5th, and bb(double flat) 7th

So once again if we look at the A major scale:

Notes of the A Major Scale

We find that ‘A diminished’ would be composed of the notes A (1st), C (b3rd), Eb (b5th), and Gb (bb7th). The fingering would be:

Listen (root notes on 5th fret):

The diminished chord has a unique property in that the root, b3rd, b5th and bb7th will share the same notes across those four keys, for example:

Diminished scalerootb3rdb5thbb7th
Key of AACEbGb
Key of CCEbGbA
Key of EbEbGbAC
Key of GbGbACEb
Notes of the Diminished Scale contain the same notes across four keys

So one diminished chord can cover four keys, since it will contain exactly the same notes in each of those four keys. This is very useful when changing keys during a piece of music, and they are also used as transition chords to pass from one chord to another in a progression, and as a substitution for dominant 7th chords.