I wanted to let everyone know that my KZ-made silver plated upgrade cables on both my ZS3 and ZST are starting to turn green.
The ZS3 cable is about 6 months old, and the ZST one about 4 months old. The older one is definitely greener than the younger one though.
I don't use it while working out either, so it's not being affected by sweat or moisture. They stay sealed in KZ plastic hard boxes whenever I'm not listening to them, stored indoors.
The cable insulation feels like PVC, which would explain the air getting in causing the oxidation.
Just thought I'd let you know, since these are the same optional silver-plated cables sold with the ZS5. So don't be alarmed if yours start discolor after around 3 months old.