Why relumes happen
Three reasons. Radium safety: pre-1960s watches used radium-226 as the lume luminophore. Radium is a radioactive isotope with a 1,600-year half-life; the alpha radiation it emits is blocked by the watch case but breaks down the binder and the dial paint over decades. Some service centres will refuse to work on a radium dial without removing the lume. Lume fallout: tritium and radium binders dry out and crumble, dropping fragments onto the inside of the crystal, blocking the date wheel, jamming hands. A relume restores function. Aesthetics: a 1970s Submariner with patchy, ugly lume can be made to look "fresh" with a relume; this third reason is what destroys value.
What relume materials look like
A modern relume uses Super-LumiNova or BGW9 applied in a particular tone. Common tones: "Old Radium" (warm orange-cream, mimics 1950s aged tritium), "Tropical" (deeper brown, mimics very aged tritium), "C3" (crisp green, no aging tone), "BGW9" (stark white, blue glow). A vintage Submariner 5513 should have warm, slightly uneven cream tritium; a relume in C3 looks too white, with too uniform tone, and gives itself away immediately. A relume in "Old Radium" is closer to original but still tends to be more uniform than period lume; period lume has tiny grain irregularities and shrink lines that fresh lume does not.
How to spot a relume
Five tells. Tone uniformity: real aged lume is slightly uneven; fresh lume is uniformly perfect. Surface finish: under loupe, original lume often shows tiny shrinkage cracks ("crazing"); fresh lume is smooth. Tonal match between hands and dial: original watches have hands and dial relumed by the factory at the same time, so they age at exactly the same rate. A relume often refreshes only the dial OR only the hands, leaving mismatched tones. Edge crispness: original lume meets the index cup edge with slight irregularity; relume tends to have either too-clean or too-messy edges depending on the watchmaker. UV behaviour: tritium has near-zero glow after 25 years (half-life 12.3 years); Super-LumiNova glows like a torch. A "tritium dial" that glows brightly under UV is relumed.
When a relume is acceptable
For collectible watches: almost never, except where the dial is safety-impaired (active radium, lume powdering inside the case, dial needs to come out for service anyway). For daily-driver vintage: a relume is fine if you accept the value loss and want to wear the watch confidently at night. For modern watches (post-2000): irrelevant; lume is Super-LumiNova and should not require relume in your lifetime. The pivotal question: "Will I sell this watch?". If yes, do not relume. If no, the watchmaker's call is yours to make.
"Service relume" vs "amateur relume"
A factory or brand-authorised service relume is technically perfect (Rolex, Omega, and Patek all do excellent relume work) but uses current production lume, which means a relumed 1970s Submariner has the same lume tone as a 2025 Submariner. Better than amateur work; still a value hit. An amateur relume by a hobbyist or a "vintage specialist" of unknown skill can be visibly bad: misaligned plots, wrong tone, runny edges, uneven thickness. Buy with caution; sell with disclosure. Vintage Rolex Service (Rolex's explicit policy) will do "service-level" relume but does not advertise that fact loudly; check the work order if you suspect.
Buying advice
When evaluating a vintage watch, UV-test the lume in person. Bring a small UV torch. Original tritium glows almost not at all; Super-LumiNova glows brilliantly. If the seller will not let you UV test, walk away. Ask explicitly: "Has this dial or these hands been relumed?" Dealers who say "I do not know" are unhelpful; dealers who say "yes, both, in 1995 in Geneva" are honest. Honest disclosure plus a 30-50% relume discount is fair; non-disclosure plus full price is theft. See also: patina vs damage and should I buy vintage?