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I was at a jewelry workshop today and saw somebody place a gold ring under an intense flame. Weirdly, the ring looked normal when underneath the flame, but glowed "red-hot" as soon as the flame was removed. The latter behavior is what I expect of a hot object emitting blackbody radiation. It makes no sense to me why the ring would not look like a blackbody object in the presence of the flame (where it could only be hotter). Maybe ions in the flame are affecting the physics at the surface and making it effectively opaque?

I didn't capture the effect on camera, but this video sort of shows the same thing happening, though not nearly as clearly as what I saw in person.

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    $\begingroup$ What do you mean "underneath the flame? Through the radiation that defined the flame? It could just be that the red frequency you saw once the flame was removed was absorbed or scattered by the flame? $\endgroup$
    – anna v
    Commented Jul 16, 2023 at 11:47
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    $\begingroup$ @annav A large flame was blown over the ring and we were viewing it while it was immersed in the flame. I should have captured on video, as the difference was striking. In the flame, it looked like a normal piece of metal with no "red hot" glow at all (the surface looked dull yellow). Without the flame, it was glowing red. $\endgroup$
    – WillG
    Commented Jul 16, 2023 at 11:52
  • $\begingroup$ This video google.com/… confirms that alone melted gold is red, it is not possible to see it through the flame because it is very intense. $\endgroup$
    – anna v
    Commented Jul 16, 2023 at 13:43
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    $\begingroup$ In this video at 20' 18'' melted gold is poured and it is yellow while hot from the melt and it turns red as it cools. So the explanation of your observation would be that while the flame heats gold has a yellow color, and as the flame stops it cools to red, $\endgroup$
    – anna v
    Commented Jul 16, 2023 at 13:48

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Hot metals are not necessarily red - at higher temperatures (above about $1000^o$C) they may be orange or even yellow - see this Wikipedia article. So the most likely explanation is that the flame heated the ring to the point where its colour was the same as its natural colour (possibly with the addition of some colour from the flame itself). Then, when removed from the flame, it cools and appears more red.

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