nuance

Although nuance is defined as "a subtle distinction or variation," the adjective subtle is frequently seen modifying the noun:

Ms. Fyfield is remarkably thorough in her psychological profiles, giving subtle nuances to characters who are mere passers-by in this psychodrama.
Marilyn Stasio, The New York Times Book Review, 27 Aug. 1989

Still, the beloved diva sustained exquisite control of her vast vocal resources, enriching line after line with gleaming tone and subtle nuance.
Martin Bernheimer, The Financial Times, 15 Nov. 2016

Since the definition of nuance already connotes subtlety—we don't speak of blatant or obvious nuances—some might regard the use of subtle as a modifier here to be redundant. But the fact of its frequent use is an indication that the connotation of subtlety in nuance might itself be too subtle to be picked up by many English speakers.

The history of "nuance" starts in Latin with the noun nubes, meaning "cloud." "Nubes" floated into Middle French as nue, also meaning "cloud," and "nue" gave rise to nuer, meaning "to make shades of color." "Nuer" in turn produced "nuance," which in Middle French meant shade of color. English borrowed "nuance" from French, with the meaning "a subtle distinction or variation," in the late 18th century. That use persists today. Additionally, "nuance" is sometimes used in a specific musical sense, designating a subtle, expressive variation in a musical performance (such as in tempo, dynamic intensity, or timbre) that is not indicated in the score.