The spectral radiation from this seems to be one single colour.
There is black, and there is golden colour.
Nothing else.

Isn't that curious?
What does that tell us.

Compare this to a gas flare: where you can read and see all the colours on a piece of paper held to it for light. See the difference?

Here you have only gold reflected. Suggesting that the emmision is a narrow band. Unlike a nice gas flare.

More like a sodium vapour lamp.