My fretboard's got a sort of...blemish on the second fret space underneath the G string, is this something to worry about? Can it be treated in any way? Lemon oil seems to make no effect on it.

It's annoying because I've only had the guitar for just over a year. It's an Ibanez RG1570. Even if it could be sorted under warranty, that's out of the question because I've had the pickups replaced, so it's void.

Has it worn down a bit? Not likely, but it's happened to my Les Paul copy and I've had that for a year and a bit.
Cam Sampbell's my hero
I think it is a bit worn down, you can see the lighter wood that's been exposed due to the string rubbing away the surface from bends and the like.
As long as it's not adversely affecting your playing, I wouldn't worry too much about it. Guitars are going to get "blemished" under use eventually. As long as it's not actually causing problems, it may just be more trouble than it's worth to fix.

You COULD try using a very fine grade steel wool to clean your entire fretboard (0000) and see if that helps polish the blemish out a little.
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