From SwissWatchExpo…
Spotlight on: the luminous materials used by Rolex in their watches.
One of the frequently touted advantages of tool watches is their legibility.
Often equipped with lume, their most practical use is to be able to tell time in the most
difficult conditions – in murky waters, inside a cave, or in the dark.
First developed around World War One, the use of lume was driven by soldiers’ need
for watches, that are easy to read in low light.
Since then, several materials have been used to make markers glow in the dark.
Today, Rolex leads the pack with Chroma-light, a material that is said to glow, more than
double the time of other luminous materials.
In this guide, we’ll take a closer look at Rolex luminous materials, and every material
they have used throughout their history.
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The first luminous material used in Rolex watches was radium; and it remained the standard
until 1963.
Before then, the effects of radiation exposure were not well understood, until the highly
toxic material caused radiation poisoning among factory workers.
At some point, Rolex even recalled Rolex GMT Master watches with radium bezels, and replaced
them with aluminum bezels free of charge.
Because radium was ruled unsafe, Rolex phased out radium altogether and replaced it with
Tritium.
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Just like radium, tritium is also radioactive, albeit with a much lower level of radiation,
and also a shorter half life.
With a half life of 12.5 years, tritium paint on watch dials and hands will lose their ability
to glow over a few decades.
Moreover, as tritium ages, its color changes, creating a yellowish patina on luminous markers
of vintage Rolex watches.
While they are substantially safer than radium, tritium watches are still radioactive, that’s
why watchmakers marked the dials with the level of radioactivity, emitted by the watch.
Most Rolex watches with tritium markers have the symbols T Swiss T or SWISS T 25 below
6 o’clock, to indicate that it uses the radioactive material.
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With tritium having its own flaws, Rolex searched for a better alternative.
In the 1990s, Japanese company Nemoto & Co developed Luminova – a photoluminescent
material that is not radioactive, making it completely safe for wear.
Rolex began using Luminova in 1998.
Aside from being non-radioactive, an added benefit of Luminova is that it doesn’t discolor
over time.
By 2000, Rolex had switched to Super Luminova, an improved version of the Luminova, that
is sold through a different company.
Both Luminova and Super Luminova need to be charged by light to give off an afterglow;
and both give off a glowing green color in the dark.
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Finally, in 2008, Rolex unveiled their exclusive photoluminescent material called
Chroma-light.
This is the first luminous material to be developed by Rolex.
Chroma-light, according to Rolex, glows more quickly and can last up to eight hours, which
is more than double the time of other luminous materials.
Moreover, rather than green, it gives off a blue glow-in-the-dark hue, which is said
to be easier for human eyes to read in the dark.
First introduced with the Rolex Sea-Dweller Deepsea, all current Rolex Professional watches
now use the blue Chroma-light display on their dials.
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Not sure what kind of lume your Rolex has?
For vintage Rolex watches, check the date of production, or look for the tritium marker
at 6 o’clock.
For modern watches, simply turn off the light and watch it glow.
Whatever color it may be, a Rolex performs well in the dark because of its superior lume.
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Want to learn more about Rolex watches?
Click on the upper right screen, for our All About Rolex playlist.
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