Part 3/8:
The core harmony of the diminished scale revolves around the diminished 7th chord, built with the intervals one flat 3rd, flat 5th (which is double flat), and flat 7th. When examining the scale, Beato points out non-chord tones or upper extensions—such as the major 9th, 11th, 13th, and major 7th—that are also embedded within the scale.
For instance, from the second degree, G, several triads and chords arise:
G diminished
G major
D minor
G Lydian (with a raised fourth degree, C♯)
G minor 7♭5 (half-diminished)
G7 (dominant seventh)
G minor 7
G Lydian ♭7
Similarly, from the fourth degree (B♭), the same pattern applies, generating B♭ diminished, B♭ major, B♭ minor, and B♭ Lydian, along with their corresponding seventh chords.