490 degrees, Yellow brown, extra hard, taps, dies.
500 degrees, Brown yellow, thread dies for general work.
510 degrees, Spotted red brown.
520 degrees, Brown purple, hard.
530 degrees, Light purple.
540 degrees, Light purple.
550 degrees, Dark purple.
560 degrees, Full purple.
570 degrees, Dark blue, half hard.
620 degrees, Blue gray, spring temper.
HIGH TEMPERATURES BY COLOR
752 degrees, Red heat, visible in the dark.
885 degrees, Red heat, visible in the twilight.
975 degrees, Red heat, visible in the daylight.
1077 degrees, Red heat, visible in the sunlight.
1292 degrees, Dark red.
1472 degrees, Dull cherry red.
1652 degrees, Cherry red.
1832 degrees, Bright cherry red.
2015 degrees, Orange red.
2192 degrees, Orange Yellow.