The Anti-reflective coating can scratch quite easily- at least a lot more easily than the crystal itself.

Yes, a lighter may work. Yes, I've heard of people taking to their watch with an abrasive pad and some type of cleanser. Personally- and I am a self-confessed coward when it comes to working on my watches- I wouldn't dream of doing either of those things.

Its a nice watch, so why not take it to an expert and have them (probably) replace the crystal?

dc