This is from a 30th anniversary 925 35. As you can see the grip has seen better days. Can anything be done to spiff this up?
If it’s raw aluminum or steel? Yes.
The first step is to determine of it’s debris caught in the knurling, or if it’s actually slight pitting. Try some cleaning solvent and scrub with an old toothbrush. If that doesn’t work, use some silver polish or other pasty compound used for deep cleaning. Some people attest success with using toothpaste, especially the kind for whitening. After that, if the marks remain, you could try using a very fine wire brush. The last resort would be to use a bristle wheel on a Dremel or micro-drill tool, and then try more force. There is one other thing which I haven’t really used in a long, long time: Naval jelly. It’s a clear gooey substance that you apply to rust that’s supposed to slowly dissolve rust and corrosion, without harming the rest of the material.