how does Superman shave, though? Does he need to scrape his face with diamonds somebody please clarify.
Superman in the Silver Age didn’t shave or cut his hair, notably this was a problem in Superman #139 (1960) when Red Kryptonite made his beard, hair and nails grow.
Note that Heat vision and X-ray vision were used as if they one and the same for a time.
In the 1986 reboot John Byrne borrowed from this story, but in this case he made it possible for Superman to trim his beard using heat vision, and a mirror made from his Space Ship.