Rolex Sea-Dweller Reference 1665: Tritium Dial vs. Rail Dial

The Rolex Sea-Dweller may not be the best-known Rolex timepiece. It indeed sits pretty behind the revolutionary Daytona, the Datejust, and the iconic divers’ watch Submariner.

However, the Sea-Dweller yet personifies what this elite Swiss-based manufacturer wishes to stand for.

The model has been in the market for the last 50years that was built originally to dive more in-depth than the Rolex Submariner being on the wrist of saturation divers.

Now, the Rolex Sea-Dweller reference 1665 of the late 1970s and early 1980s appear virtually identical at a glance.

However, the fact is that both watches have unique differences between them. And interestingly, the difference lies on their dial.

Today, let’s take a closer look at the Sea-Dweller 1665 with Tritium and Rail dials and find out the key features that make them unique.

The Rolex Sea-Dweller 1655: Tritium Dial

The name “Tritium” indicates a significant element of the dial. So, what is it?

Rolex applied a luminescent element “Tritium” to the early iterations of the Sea-Dweller. And, the material is radioactive.

• Thus, the manufacturer wanted to indicate how much it has used the luminescent radioactive element.
• Eventually, Rolex engraved code on the watch’s dial to specify it.
• A Tritium dial consists of the “T” engraving under the 6 o’clock hour marker.

However, Rolex offered two types of Tritium dials to the Sea-dweller:

• One, the Tritium Swiss- T <25 Dial
• Second, the Tritium Swiss T <25 Dial.

The Swiss-T <25 designates that the watch is Swiss-made and has tritium levels emitting less than 25 mCi.

On the other hand, the T Swiss T<25 marking on the dial specify that the watch is Swiss-made and has tritium levels emitting less than 7.5 mCi.

However, it is significant to note that:

Some Sea-Dweller 1665 watches can flaunt only “Swiss Made” or “Swiss” markings on their dial.

This indicates that the watch doesn’t possess a luminous radioactive material.

Moreover, many service dials of later-era have “T Swiss T <25” markings. But the fact is they come with LumiNova hour markers.

Also Read: Review: The Refurbished Rolex Sea-Dweller

The Rolex Sea-Dweller 1655: Rail Dial

The Rolex Sea-Dweller Rail Dial is ideally much rarer than any other Sea-Dweller 1655 dials. Why?

The fact is that Rolex produced this Rail dial for only two years.

Between 1977 and 1979, Rolex produced the Sea-Dweller 1665 with the “Officially Certified” and “Superlative Chronometer” text engraved above the 6 o’clock hour marker.

If you compare both the dials, you will notice:

• In Tritium dial, the letter “C” in “Chronometer” and “Certified” are not in line.
• However, they are almost perfectly lined up or parallel on the Rail dial.
• While the arrangement appears like the rails on a train track, it is dubbed as the “Rail Dial”.

The Rolex Sea-Dweller Rail dial is incredibly challenging to find.

They are found in vintage models, and also, Rolex has produced a very few examples of it in the first place.

Now:

The Sea-Dweller Rail Dial comes with a Tritium indication at the 6 o’clock position. You will notice that it features the “T Swiss T <25” marking.

Overall, the fact is that all Rail dials are also Tritium dials. On the contrary, all Tritium dials are not Rail dials.

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Thus, to sell your Rolex Sea-Dweller or any other Rolex model to us,

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Also Read: Explore The ‘Star’ Vintage Rolex: The Double Red Sea-Dweller