Dang, Lani ... I went and Googled up a bunch of photos of Doxas and it seems many of them DO have lume in that dot. All the old ones I've been investigating have been black.
See what happens when you take Deltatahoe's advice? Pain, confusion, destruction, paint wildly misapplied... will the horror never end?
It seems the really old pieces are all black, and that's likely because (like yours) the bezels have been repainted many times. Certainly you can put lume in there, and it's possible they came from the factory thus endowed. But to my eye the black spot looks "correct."
Imagine a DRSD with a shiny new green pearl in the insert, vs. a gnarly old speckled pearl. There's your answer.