Since its introduction, luminescence has arguably been one of the top “cool” factors of a wristwatch. The glow is incessantly captivating, and nowadays come in colors other than the classic green. As you might have guessed, "lume" is short for the luminescence or the luminous glowing solution normally applied on hands, hour markers, bezel or even on the dials themselves. But how did it all come about, and what is it now? While originally published on our blog back in 2015, we’re back with an update on all things lume.

Did you know that lume was originally powered by radioactive material? In the early 1900s, a mix of radium and zinc sulfide was coated on watches to achieve the glow, used as a tool during wartime. As time went on, tritium was used an alternative. Of course, this was eventually found to be an unsafe practice. Today, the most common material used for lume is a non-radioactive pigment or solution that is charged by light (photoluminescence).

While lume is available in a variety of colors, in the light its presence may go unnoticed. In some cases however, based on the color of the glow, it may possess a slight tinge of green or blue. Currently there are many different manufacturers of lume, with different grades of photoluminescent pigment. For instance, our diver watches (like the AA02) are treated with Nemoto LumiNova®. LumiNova® has been around for over 25 years and is known for its bright and lasting pigment; so much in fact that the Swiss gained a rights license to manufacture it in Switzerland under the name Super-LumiNova®.

While luminescence is not common to classic or dress watches, few designs may incorporate a small amount to the dial and/or hands. In contrast, sport and diver watches feature lume more prominently—in fact, it is an essential part of diver watch design. Legibility is one of the most important attributes of a dive watch, as brightness is essential as you descend further, and endurance of light is needed for the extent of the dive. As we’ve mentioned in other posts, the advent of the dive computer renders the dive watch as a novelty, but knowing the practical use of lume provide an understanding of diver design.