Thats a big "chip", sounds like a good place to put a decal, sticker or another knob, seriously if you do want to try to repair it, you'll need to find out what kind of finish is on the guitar, acrylic laq., epoxy, catylized , water base laq. etc, some are easy to repair, some are just about impossible, I don't know what Ibanez uses, if you find out, get back to me OK?