In the Fall of 1997, IWC introduced a new model line, called “GST”. Within the GST model line-up was a classic diving watch, the GST Aquatimer ref 3536.

With a black dial signed “T Swiss Made T”, the early IWC Aquatimer GST used a mix of both Tritium and Super Luminova elements on the dial and hands. Tritium was used on the hands, the 12 o’clock marker and the index dot of the bezel. Whereas, Super Luminova was applied on the rest of the markers. Over a decade later, this is how the luminosity has endured:

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