At first glance, the watches look almost identical. And that’s pretty much true, since both of these are replica Rolex Sea-Dweller ref. 1665 watches from the late 1970s and early 1980s. However, there is one unique difference between the two watches – the dial. Here we will compare the tritium and rail dial ref.1665 this is only a few years apart and the key details. Let’s take a closer look!
This is not a fancy name for a dial design, but an indicator of an important dial element. Tritium, a luminous material used in these early ocean dwellers’ watches, is actually radioactive. So, to determine how much of this potentially dangerous substance was used, Rolex used a code on the dial to represent it. You can always identify a tritium dial by the “T” mark at the bottom, under the 6 o ‘clock mark.
Moreover, some later-era service dials are marked with ‘T Swiss T <25' but they actually feature LumiNova on their hour markers. To be clear, 'SWISS' can also indicate radium, but this was only used on rep
lica watches in the early 1960’s, and the Sea-Dweller was not released until 1967.
While there are so many different dial variations for the fake Rolex Sea-Dweller 1665, the Rail Dial is incredibly rare since it was only produced for two years. Between 1977 and 1979, the ref. 1665 could be found with a particular feature that involved the ‘Superlative Chronometer’ and ‘Officially Certified’ lines of text that appear above the six o’clock hour marker.
You see, if you look closely at the image above, you’ll notice that the ‘C’ in both ‘Chronometer’ and ‘Certified’ line up almost perfectly. Take a look at the Tritium dial below for comparison and you’ll see they’re not in line at all. They are almost parallel on this dial (kind of like the rails on a train track), hence the ‘Rail Dial’ nickname. These wines are hard to find today, both because they are old and because few were made.
Now, if you keep looking at the six o ‘clock position in the figure above, you’ll notice that this dial also has a tritium mark. Therefore, all rail dials are actually tritium dials. However, not all tritium dials are rail dials.