2.6K views · 63 reactions | How to Form a Diminished Chord To form a diminished chord, combine the 1st, flat 3rd and flat 5th tones of the major scale. For instance, to form a C diminished chord, start with the C major scale, C D E F G A B C and play note 1, C, the flat 3rd, Eb (1 semitone lower than E) and the flat 5th, Gb. C-Eb-Gb is a Cdim chord (C diminished). #piano #pianolesson #musictheory #chords #pianotutorial | Piano-Keyboard-Guide.com | Facebook