Guide
Watch Lume Explained
BGW9, C3, Old Radium — what each lume type actually does in the dark.
Quick answer: Lume is the glow-in-the-dark paint on a watch's hands and markers. Modern watches use Super-LumiNova, which charges in light and glows for hours without radiation. Brighter, longer glow comes from thicker application and the C3 or BGW9 grades.
Shop Dive Watches →How lume works
Strontium aluminate pigments absorb light and slowly release it. It is completely safe — unlike the radium and tritium paints of older watches.
Common grades
- C3: green glow, the brightest
- BGW9: blue glow, white in daylight
- C1 and Old Radium: vintage-style cream tones, slightly dimmer
Getting the best glow
A few seconds under a torch or direct sunlight charges lume fully. It is brightest in the first 30 minutes and fades gradually overnight.
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Frequently Asked Questions
Is watch lume radioactive?
No. Modern Super-LumiNova is non-radioactive.
How long does lume last?
It glows brightly for minutes and visibly for hours; the pigment itself lasts decades.
Does lume wear out?
Not noticeably over a watch's lifetime.