Name the colour chord

Four more triad shapes to read. Diminished stacks two minor thirds: 3 + 3, cramped and tense. Augmented stacks two major thirds: 4 + 4, evenly stretched.

The suspended chords have no third at all. Sus2 puts a whole tone above the root: 2 + 5. Sus4 puts the fourth there: 5 + 2.

The outer notes help: a diminished triad spans 6 semitones, an augmented one 8, both sus chords a perfect 7.

dim = 3+3 · aug = 4+4 · sus2 = 2+5 · sus4 = 5+2

Two cramped thirds from C: C diminished.

Practise this in the trainer — it opens with this lesson the first time the concept comes up.