The 1680 was the first Submariner with a date, which was a big deal at the time. To make room for the date window, Rolex added the now-iconic Cyclops magnifier on the acrylic crystal—something that’s become a signature ever since. What really sets the early 1680 apart is the red “SUBMARINER” text on the dial. Rolex only used red lettering for a short period in the late ’60s and early ’70s, and by the mid-1970s it was gone. That brief production run is why collectors nicknamed it the Red Sub and why it’s so desirable today.