- This page is about chromas in general. For that in the diatonic scale, see Chromatic semitone.
The chroma (precisely the moschroma) of a mos scale is the interval that is the difference between the large step and the small step in the scale. In particular, the chroma in the diatonic scale is the chromatic semitone, or augmented unison, for example, the interval of C-C#.
In staff notation, alteration by the chroma can be represented by the sharp (#) or flat (b), as is shown above. In diamond-mos notation, it should be noted that they are reserved exclusively for the diatonic scale, whereas am (&) and at (@) are used for other mos scales.
Moving one note in a mos scale by a chroma leads to a modmos scale if the result is not just a transposition of the original mos scale.