Tarnish
Verb
- To dull or destroy the luster of by or as if by air, dust or dirt
- To detract from good quality of
The word is used In A Rose for Emily by William Faulkner of the paragraph 5, “A tarnished gilt easel before the fireplace stood a crayon portrait of Miss Emily’s father”.
The gold color frame of Miss Emily’s father portrait was detracted from original color caused by air or dust and it looked like the color of the penny coins become tarnish when changing between hands so many times.
http://www.merriam-webster.com/dictionary/tarnish