The World of Luminescent Watches: The Story Behind Luminova Technology

The World of Luminescent Watches: The Story Behind Luminova Technology

Luminova, Superluminova, Chromalight... These names frequently come up in discussions among watch enthusiasts. They all have one thing in common: they describe different types of luminescent materials that can be applied to watches and their hands.

Lume, the short form of luminescent material, is a substance applied to watch dials and hands to improve readability in low light conditions. Initially experimented with on pocket watches in the early 1900s, lume gained popularity during World War I.

What are the benefits of Luminova?

  • Improved readability in dark environments and at night
  • Increased safety for diving
  • Aesthetic enhancement of the watch through luminous details
  • Maintains the traditional aesthetics of watches while providing modern functionality
  • Different colors and brightness levels offer variety and customization options for watch designs

How does Luminova actually work?

Luminova works by using a special chemical called strontium aluminate. This chemical is enriched with tiny traces of other substances such as europium and dysprosium.

Due to its composition, Luminova has the ability to absorb light and later emit it in the dark. To activate this property, the material must be charged with sufficient light beforehand. The subsequent luminosity depends on the amount of light absorbed.

The brightness and duration of the Luminova effect depend on the intensity of the light source. The longer the darkness lasts, the fainter the glow.

The first watches with luminescent hands – Playing with fire!

The development of Luminova marks a significant milestone in the history of luminescent materials for watches. Previously, materials like radium were celebrated for their self-luminous properties. However, it was later discovered that radium is radioactive and poses serious health hazards. Tragic events like the case of the "Radium Girls" illustrated the extreme risks of this substance.

In response to safety concerns, alternatives with lower radioactivity were introduced, including promethium and tritium. The latter, a radioactive isotope of hydrogen, became the industry standard from the 1960s onwards. Despite its effectiveness, tritium-based paints were eventually phased out in 1998 due to safety concerns.

Luminova – The first safe luminescent material for watches

In the early 1990s, Luminova was developed in Japan, marking a breakthrough with its non-radioactive composition. Alongside Superluminova, a joint venture between Japanese and Swiss companies, Luminova replaced tritium as the industry standard. Known for its ability to absorb and emit light energy, Superluminova offered improved durability and safety compared to previous materials. This development brought about a new era of safety and performance in the world of luminescent materials for watches.

Overview of modern luminescent materials for watches:


  • Developed by Nemoto & Co., Luminova uses strontium aluminate-based compounds for luminescence.
  • Superior brightness compared to previous techniques.
  • Does not provide a radioactive signature.
  • Variants include different grades and colors, with C3 being the brightest and BGW9 offering aqua afterglow.


  • A Swiss development of Luminova, Superluminova stands out for its higher performance and durability.
  • Grades like X1 demonstrate superior brightness and extended glow duration compared to standard formulations.
  • Widely used by leading watch brands for their reliability and versatility.

Chromalight (Rolex):

  • Rolex's proprietary luminescent material, Chromalight, uses a formula similar to Superluminova.
  • Known for its distinctive blue glow and extended longevity, Chromalight competes with the brightest lume variants.
  • Speculations suggest that its formulation is similar to the BGW9 class of Superluminova.

Understanding the intricacies of luminescent materials in watches reveals the meticulous craftsmanship behind these timepieces. From the hazardous beginnings of radium to the innovative advancements of Superluminova, the evolution of lume reflects the pursuit of functionality and safety in horology. As technology advances, so does the brilliance of luminescent materials, paving the way for future innovations in the world of horology.

A watch with two different Luminova colors?

    With the Lumatik Automatic, we are now proud to introduce the first STERNGLAS timepiece featuring two different Luminova colors: white on the numbers and orange on the geometric indices and hands. On the back of the watch, you'll find fine details such as blued screws, which are typically found in luxury watches. The Lumatik is powered by an automatic movement with up to 60 hours of power reserve. You can comfortably set your timepiece aside for a day without worrying about it stopping and having to reset it.

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