Horology glossaryDefined term / lume
Lume
Luminescent material applied to hands, hour markers, and sometimes the bezel so the dial can be read in low light or darkness.
Authentication note
Why this detail matters.
The lume material a watch uses depends on its production era: radium, then tritium, then Super-LumiNova follow a roughly known timeline, so the lume material and glow color should be consistent with the watch's claimed age. A vintage watch with implausibly bright modern lume, or a lume plot that doesn't match its reference, both warrant a closer look.