Patina

“Patina” (PAT-n-uh or puh-TEEN-uh) – from the Latin for “a dish” – is the color or incrustation, as a result of natural aging, that changes the appearance of an object’s surface. The word is also used to refer to a superficial layer or exterior.

Example (as used by Gary Kinder in Ship of Gold in the Deep Blue Sea): “[The ship] was sleek and black, her decks scrubbed smooth with holystones, her deckhouses glistening with the yellowed patina of old varnish.”