Somehow the dial lacquer has deteriorated with interesting effect: rainbow colour reflection. I saw similar phenomenon happened to Ashley/dsio Cal 320 Gold chronograph. My other Grand Luxe does not suffer this symptom.
No known phrase for this symptom I've read anywhere. So for now I call that "rainbow dial", hopefully it will catch popularity as "patina" or "ghost bezel" and add value to the watch
馃槣 .
On second thought, this symptom is relatively rare to be found and accepted as mainstream WIS phrase
馃檨 .