That simply means it must melt below 600°C.

A quick wiki check says it melts at 660. I guess if you’re in a really dark room, you could see the glow.

Real bodies are gray, not black.

Eventually will glow human eye visible if you keep heating it past useful temperatures. 1000’C+ starts getting red hot.

Doesn’t emit light as readily as iron does, especially with iron’s oxide layer building up when heated.