Well, I appreciate the input, but I remain skeptical of the burn/lighter theory.
As I said, the pictures came out darker than in hand. Overall, the color is closer to silver/gray than what appears.
The marks aren't soot, as they don't wipe or wash off.
It could be the copper plating blistering off due to heat, but here's a couple of close up which don't show any obvious blistering or heat related rippling.
Thanks for your time!