Discolored thumbstuds on new knife?

[Julian Williams]

Recently bought a 0393 from SMKW. Noticed the thumb studs have a yellowish and scratchy film on the tops. Kinda hard to see with my camera, so I put another ZT beside to help show the difference. Tried wiping with rubbing alcohol and WD40 with no avail. Not a big deal, but it’s annoying on a new knife. What could cause this?

 

[AntDog]

Try dish soap. If whatever it is is oil based that might take it off.

That really wouldn’t concern me at all though. Who knows what kind of pot metal thumb studs are made out of.