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Good evening everyone!
This column talks about mechanical watches from an engineer's perspective. This is the 45th installment.
"The Evolution of Luminous Paints: Tritium, Luminova, Chromalight"
I will be talking about this topic here.
When choosing a luxury watch, luminous paint plays a very important role.
The indexes and hands glow dimly in the dark. Although the luminous paint no longer functions as such, some watches undergo a subtle aging process, increasing their value. In addition to their practicality, the luminous paint also greatly affects the overall look of the watch.
This time, I would like to explain the differences and appeal of three representative types of luminous paint that have evolved over the years: tritium, Luminova, and Chromalight, from the perspective of a watch lover.
Tritium: Vintage Flavor
First, there's tritium, a familiar name to vintage enthusiasts.
This luminous paint was used on many mechanical watches from the 1960s to the mid-1990s, and is characterized by the fact that it contains radioactive materials. You'll find inscriptions such as "T SWISS T" or "T<25" on the dial.
Tritium characteristics
・Self-luminous ・Light intensity weakens over time ・Some change color from cream to orange over time
This "change over time" is the greatest attraction of tritium. Evenly darkened indexes and hands are highly sought after, and increase the value of the watch.
However, because it contains small amounts of radioactive material, it is not currently used due to safety standards.
*1966 Submariner 5513
*1978 Explorer "Ref. 1016"
Even though they are all classified as tritium, their reaction to UV light varies depending on the year and model, and they have unique characteristics in how they change over time...these are also points that appeal to enthusiasts.
Luminova: The modern watch standard
Next, I'd like to introduce "LumiNova".
It has rapidly gained popularity since the late 1990s as a non-radioactive luminous paint that replaces tritium. Dials usually have the words "SWISS" or "SWISS MADE" printed on them, and with a few exceptions, the "T" for tritium is not included.
As of 2025, it is still used by many brands and is considered the "modern standard for luminous materials." As many of you may already know, Luminova is a paint developed by a Japanese company called Nemoto Specialty Chemicals. As a Japanese person, I'm very proud of this.
Luminova features
・Non-radioactive and safe ・Storage and glow (phosphorescent type)
- The light is bright green and fades over time - The color is generally white to slightly greenish
It is highly practical as a luminous element and has excellent visibility in dark places.
However, unlike tritium, it does not change over time and the color remains almost the same even after many years. For this reason, vintage lovers may find it lacking.
Chromalight: Rolex's unique "blue luminous"
Finally, we would like to introduce Chromalight, which Rolex began to fully adopt around 2008.
This is Rolex's proprietary luminous paint, and its greatest feature is that it emits blue light. Compared to conventional green luminous paints, it is said to be gentler on the eyes, even in the dark, and easier to read for long periods of time.
Chromalight Features
・Non-radioactive ・Luminous ・Blue light emission ・Long-lasting luminescence ・Used in many current Rolex watches
It was first adopted in professional models such as the Deepsea, and is now used in almost all Rolex models, including the Datejust. When viewed in the dark, the indexes and hands glow a cool blue, giving the impression of a truly "latest Rolex."
The image above shows a watch with Chromalight indices and Luminova hands. Comparing them like this, you can clearly see the difference in how they glow in the dark. Like Luminova, this watch also shows almost no change over time. It is not a luminous material that you can enjoy for its future "flavor."
How will materials such as the Cerachrom bezel and Chromalight luminous material, which have made incredible advances in functionality and durability, be received in the vintage watch market decades from now?
It's fun to imagine these things while choosing a watch.
summary
What did you think?
I hope you can see that the type of luminous paint alone can have a big impact on the popularity of a watch.
・If you want to enjoy a vintage feel → Tritium ・If you want to use it every day and prioritize practicality → Luminova ・The latest Rolex worldview → Chromalight
It's not a question of which is the best, but rather the value changes depending on which era of watch you want to enjoy. We hope you will choose one that suits your preferences.
We hope that this article has been useful to you and has sparked even a little interest in luxury watches! If you have any questions, please feel free to ask us directly and we will be happy to answer them. We look forward to your visit and inquiries.
Please look forward to the next one!
