Polywatch is for acrylic crystals only, don't know what you watch has, but if acrylic use a fine sand paper to remove the scratches then the polywatch.
I've never been able to effectively remove scratches and polish a mineral crystal by sanding and then polishing with diamond paste, but others have.
Easier just to change the crystal then.
These citizens are a bit hit and miss with sizes for replacement crystal - they can be tricky sizes like 38.6 etc- they are pence on cousins though if you can find the right size
You'll find that hard to polish out- looks like it's got some chips at the top too