1967 thin-case Double Red Sea-Dweller 1665, Mark II dial.

In Autumn 2018 we were approached by an existing client to ask if we would advise his father, who had a Double Red Sea-Dweller. We were delighted to help and appraise the watch comprehensively for him.

He had bought the watch around fifty years earlier for a couple of hundred pounds, simply because he liked it; his father had a gold Oyster on a President bracelet. He had been wholly unaware of its later significance until on holiday in Florida a jeweller offered him a large amount for it, then more recently a colleague with a modern Sea-Dweller had remarked upon the watch. He researched what he could, but knew he needed some guidance.

The watch is a Sea-Dweller 1665, the model introduced with a Helium Escape Valve (HEV) designed to prevent saturation divers’ watches from exploding when they resurface. It came about as the pioneers of commercial diving in the 1960s, most notably the French company Comex, pushed to greater depths for longer – driven, perhaps, by the flourishing oil industry in places like the North Sea.

This watch is one of the earliest made. It has a 1.7 million case number, belonging to a small batch of which we have extensive records. All of this batch appear to have case-backs marked internally with the date code IV.67, denoting manufacture of that part in the last three months of 1967. It correctly also bears the last three digits of the main case number, helping ensure that this watch keeps its original back whenever opened for service work.

The main case number is contemporary and fits with a 1968 final assembly, the watch probably selling in the year or two that followed.

All of these early watches will have the word ROLEX written in straight text across the exterior of the case back. This is true of most Double Reds, although there is a small range of the last ones, with low 5m case numbers, where the word ROLEX is correctly written in a curve, as on all later “Great White” 1665s.

The earliest watches might be found with “PATENT PENDING” on the case-back, such was the cutting edge nature of the design. Those watches can be worth considerable amounts, especially if their dials are good. By the time of this watch, however, Rolex must have obtained its patent and the back is thus marked accordingly:

Let us look at the dial more closely. This version is known as the Mark II:

You will note how light the dial appears when compared with the black bezel insert around it. It is a particular phenomenon with the Mark II dials that they have commonly faded to a chocolatey colour, almost purple when viewed through a jeweller’s loupe.

Consider the unique style of “smudge” coronet below, which is somewhat imprecisely printed. Note the minimal “mouth” at its base and the extraordinary “dog-leg” top to the second of the five prongs. Only a Mark II will look like this:

The text in the lower half of the dial is similarly indicative of a Mark II. This cannot be a Mark I, as the line “SUBMARINER 2000” is in text smaller than that of the line above. It cannot be a Mark III as the letter “S” is shaped differently and the relative positions of letters are not the same. It cannot be a Mark IV, as that has a “closed” 6 in the 610m depth rating. It cannot be a Mark V (service replacement) dial, as that version also has a “closed” 6 and the units of depth are italicised.


The world of Rolex collectors, albeit none more than this writer, is indebted to the categorisation of Double Red Sea-Dweller dials so comprehensively formulated by my friend, Ed Delgado in America.

This batch of DRSDs are what is called “thin case” models, being slightly slimmer in depth around the midriff. This can be hard to identify without a comparison to hand, but if you put a later DRSD against it you will see that the amount of metal above the HEV (shown below) is noticeably less on a thin case, while the shoulder guards protecting the crown on the other side reveal a similarly striking contrast.

The watch is powered by the dependable 1575 calibre movement, though as usual the bridge is marked simply “1570,” this being the  base calibre number from which the version with Date complication derives.

The movement is uniquely numbered, the prefix “D” further confirming that it is a movement with Date feature.

You may have noticed from the images above that the indices on the dial appear darker on the left hand side. It may well be that decades of wear poking out under a shirt cuff have exposed the right hand side to greater damage from ultra violet light. Under magnification, it seems that the luminous tritium has actually degraded to almost nothing on the right hand side, revealing the printed white base underneath…

…while on the left much more tritium remains, to display the discoloration typical of ageing:

When our client’s father first approached us, his watch was in the hands of Rolex UK who were quoting extraordinary sums when all he wanted was basic, mechanical service. He had them return it undone and accordingly it bears their service mark with “XX” coding inside the case-back. Look out for the much worse “XXX” — that’s when Rolex refuse to do any work for you!

Our visitor, head spinning by now, was intrigued to see inside his watch and learn a little of what these hidden scribings meant. For five decades he’d not known what excitement lay under the bonnet!

It was a privilege to examine such a rare piece. It is imperfect and the dial’s condition will have a significant impact on the value it might have had, but still it is a piece of commercial diving / Rolex history.

We are always looking to purchase such rare pieces. If you have a professional Rolex model (Submariner, GMT-Master, Sea-Dweller, Milgauss, Daytona etc) from the 1950s or later, we would be delighted to appraise it without commitment on your part. Simply contact us through this website.

Haywood Milton, October 2018

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