Chromatism always -
(a) operates in the direction of the Voice-leading of a given Orbit:
if a note resolves downward, it will be flattened;
if a note resolves upward, it will be sharpened;
(b) requires the necessary "space":
if a note resolves a whole tone, chromaticism is possible;
if a note resolves only a semi-tone, chromaticism is not possible;
(c) makes a chord more complex;
(d) makes a chord more powerful;
(e) produces an irreversible result:
once a note (or chord) is chromaticized, it stays chromaticized.
A chromaticized note always bears the same note name as the original diatonic note.
All of these properties of chromaticism will become clearer as we see examples.