On 25 Aug, 10:59, jim wrote:
number 2 son has now managed to scratch both SWMBO and my mobile
phones by rubbing them on the wood floor where grit etc has worked
it's magic and scratched them.

Micromesh abrasives. Expensive, but work very well on plastics. Easier
to achieve a good result with than polishes.

For a phone though, I'd probably just use wet Wet & Dry paper. 1200
grit is common enough, you can go finer if you go to a car refinishing
place. That's adequate for phone screens, if not for sunglasses.