The so-called Draper point is the temperature where one sees an object (regardless which substance) glowing dull red. Many sources say 525ºC but other 470ºC. Depends on how dark your environment is.
I checked more times in a cooling furnace in a dark room the temperature when I was still seeing very dark red glow. I measured 480ºC.
In 'normal' ambient light (1000lx), even just molten aluminum (660ºC) does not glow or very dull red.
One time I did an experiment melting copper in a flame in bright sunlight (> 40000lx) where I could really see the pink luster of the liquid copper and barely see the orange red incndescence. See here: