I’ve had pretty good luck removing the few scratches on my Series 6 natural Ti case with a pencil eraser. Scrub over the scratch for a few minutes with the eraser and then rub with a damp micro-fiber cloth until clean. Under bright light they are still there but very faint.I don't know why so much concern about scratches, etc. on natural titanium. To me they just add to the character. Despite the case scratches of my series 6, the crystal is unblemished - that's most important to me.