Patina (noun)

1. A green or brown film on the surface of bronze or similar metals, produced by oxidation over a long period.
2. A surface appearance of something grown beautiful especially by long exposure or use.

Origin:

Late 16th century: from latin, literally "pan", from greek patanē, from patos "shallow dish".

Examples:

1. The statue had a beautiful green patina that was the result of years of exposure to the elements.
2. The antique vase had a rich patina that was evidence of its age.
3. The patina on the copper roof had become dark and weathered over time.
4. The patina of the old guitar gave it a sense of history and character.
5. The patina of the wooden floorboards added warmth and character to the room.