Lume (Leuchtmasse)
The light-emitting material applied to a watch's dial markers and hands for low-light visibility. Tritium dominated until the late 1990s; modern watches use Super-LumiNova. Lume ageing is a key originality signal for vintage trading.
Lume (short for luminous compound; German Leuchtmasse) is the light-emitting material applied to a watch's dial markers, hands, and bezel indices for low-light visibility. Lume technology has evolved through several generations, each with distinguishing characteristics that matter for authentication and originality.
Lume generations
- Radium (pre-1960s). Self-luminous through radioactive decay. Phased out for safety reasons. Old radium dials are mildly radioactive and can show characteristic burn-out patterns on the dial surface.
- Tritium (1960s to late 1990s). Less radioactive than radium but still self-luminous. Ages predictably to creamy yellow, tan, or amber over decades, producing the characteristic vintage "patina" lume look. Dials of this era are marked "T SWISS T" or "T < 25" or similar to indicate tritium content.
- Super-LumiNova (late 1990s onward). Strontium aluminate phosphor charged by ambient light. Not radioactive. Comes in many colour variants (BGW9 white, C3 green, vintage off-white). Does not age the same way as tritium — it stays bright through decades but lacks the warm patina.
- Chromalight (Rolex proprietary, 2008 onward). A specific Super-LumiNova formulation by Rolex that glows blue rather than the standard green. Used across modern Rolex sport references.
How lume informs authentication
- Tritium versus Super-LumiNova mismatch. A 1970s Submariner with bright white-glowing lume is on a service dial. Original tritium lume should be aged.
- Even ageing. Original tritium plots and hands age in step. Mismatched colours between dial plots and hands indicate a part has been replaced.
- Lume colour consistency across the dial. Uniform creamy tone across all plots is original; spotty or partial ageing can be damage rather than patina.
- UV reactivity. Modern Super-LumiNova reacts characteristically under UV. Counterfeit lume often does not match the OEM phosphor's UV signature.
Lume in valuation
For vintage Rolex, AP, Patek and similar premium brands, original well-aged lume often carries a 20 to 50 percent premium over equivalent reference with replaced lume or service-dial replacement. Tropical lume (heavily creamed) on a tropical-dialed Submariner or Daytona can multiply value many times over.
Related: patina, service-dial, frankenwatch, provenance.