The Seadweller 16660 – “Triple 6” is one of the most interesting and noteworthy models of the whole Seadweller series.
Its undeniable historical importance derives from the fact that the Triple 6 is a sort of “transitional” model that marked the passage from old-style steel sports models characterized by plastic glass and the more recent ones coming with the stronger sapphire crystal.
The Seadweller 16660 was in fact the first professional steel Rolex appeared with the significant sapphire crystal technical innovation.
Furthermore, compared to its predecessor, the Seadweller 1665, the 16660 is equipped with a more efficient and performing calibre as well as a new bracelet with end links that are no longer empty, but solid and therefore more resistant to stress and shocks.
Rolex 3035 caliber macro shot
Rolex 3035 caliber components
Solid end Links ref.592 fitted on a 16660 Seadweller
Even the water resistance feature of the watch was significantly improved as the 16660 has a guaranteed waterproof resistance up to 1220m, which means twice that of the previous 1665 reference.
This exceptional result was achieved not only thanks to the new sapphire crystal, but also because a new Patented Gas Escape Valve (HEV) was adopted in reference 16660.
The new 16660 HEV disassembled (pic courtesy SteveB from O&P)
A Rolex gadget showing the HEV valve fitted in the watch case (pic courtesy SteveB from O&P)
A comparison between the old 1665 HEV (reference v50) and the new 16660 HEV (reference v53)
The differences between the 2 HEV versions are enormous, that of 1665 was efficient and well built, but that of 16660 is a true masterpiece of micromechanics.
Despite being in production for no longer than 10 years, the Seadweller Triple 6 appears in multiple versions, different according to the year of production.
Initially equipped with matt dials and “pallettoni” indexes more typical of the 1665 reference, the watch then mounted the so-called gloss “bicchierini” dials, a further update meant to give a more modern and professional feel to the watch itself.
An exceptional example of Rolex Seadweller 16660 “Pallettoni” dial
An exceptional example of Rolex Seadweller 16660 “Bicchierini” dial
Another fact that is unknown to most is that even the caseback can be found in a number of different versions.
While going into depth in the study of this reference, it appears there are countless existing configurations that sometimes differ in small details which, if carefully analysed and listed, pigeonhole each other.
The purpose of this topic is to draw up a clear and detailed list of the different casebacks mounted on the Seadweller 16660 during its years of production.
As mentioned above, that of 16660 case-backs is not a well-known topic and I believe the matter has never been approached in a such a precise and detailed way before.
I really hope my study may be useful and guide you to more conscious and careful purchases.
In order to achieve a correct classification and temporal location of the casebacks of the 16660 reference, it was necessary to carry out a double analysis, both on the external and internal graphics of the case-back.
The reason for this choice was dictated by the fact that a given internal graphic almost never corresponded to a single and precise external graphic.
However, with this “double-fold” method it was possible to obtain and find out the correct external-internal combinations for all the serials of the 16660 reference.
Let’s see the different graphics of the external caseback over the years.
THE FIRST SERIES OUTER CASEBACK (estMK1).
Characteristic :
– There is only one “Crown” located between the words “Rolex” and “Oyster”
– The word “Original” is not present before the writing “Gas Escape Valve”.
– The “G of “Gas” has a very open and elongated shape if compared with later series graphics.
THE SECOND SERIES OUTER CASEBACK (estMK2).
Characteristic :
– There are two “Crowns” located between the words “Rolex” and “Original” and “Oyster” and “Valve”.
– The word “Original” is present before the writing “Gas Escape Valve”.
– The “G of “Gas” still has a very wide shape, but less elongated if compared with the previous series graphics.
THE THIRD SERIES OUTER CASEBACK (estMK3).
Characteristic :
– There are two “Crowns” located between the words “Rolex” and “Original” and “Oyster” and “Valve”.
– The word “Original” is present before the writing “Gas Escape Valve”.
– The “G” of “Gas” has a less open, less elongated and more rounded shape.
– There are several letters of the writings including the “C” of “Escape” and the “O” of “Original” which have a totally different shape from the previous series.
THE FOURTH SERIES OUTER CASEBACK (estMK4).
Characteristic :
– There are two “Crowns” located between the words “Rolex” and “Original” and “Oyster” and “Valve”.
– The word “Original” is present before the writing “Gas Escape Valve”.
– The “G” of “Gas” has a very rounded shape.
– The serifs disappear almost completely, it is a more modern graphic.
– The graphics tend to be closer to the the border of the case back.
– Some rare specimens also have a much lighter engraving which sometimes can be barely visibile.
THE FIFTH SERIES OUTER CASEBACK (estMK5).
Characteristic :
– In some very rare specimens no engravings can be found on the external caseback.
So for the moment we have cataloged 5 types of external graphics that we summarize below :
Having understood the different graphics characterising the external part of the casebacks in the various production batches of the 16660 reference, it is now time to have a close look at the internal ones.
The internal casebacks can be substantially divided into 3 different series depending on the writing of the word “PATENTED” which can be present, milled or even absent.
For those who don’t know, I would like to explain why the word “PATENTED” has undergone these changes and the reason is that, at the start of the 80s, Rolex’s patent of the famous OYSTER case expired.
For legal reasons, after the expiry of this patent, Rolex was no longer authorized to use the term “PATENTED” on case-backs.
So:
– Until the early 1980s, not only on the 16660 but on all Rolex OYSTER cases, we ALWAYS see the word PATENTED on the caseback.
– For a short transition period and on the casebacks already produced and engraved before the expiry date of the patent, the word PATENTED is present and MILLED.
– After the disposal of these “transitional” case-backs, the word PATENTED is no longer engraved on the case-backs and disappears completely.
Bearing this in mind, we’ll now see in detail the 3 series of internal case-backs.
THE FIRST SERIES INNER CASEBACK (intMK1).
Characteristic :
– The word “PATENTED” is present.
THE SECOND SERIES INNER CASEBACK (intMK2).
Characteristic :
– The word “PATENTED” is milled.
THE THIRDS SERIES INNER CASEBACK (intMK3).
Characteristic :
– The word “PATENTED” is not present.
For the internal graphics we have therefore listed 3 types that we summarize below :
At this point we have classified all types of case-back graphics, both EXTERNAL and INTERNAL which, in our opinion, have alternated over the years.
Time has now come to combine this information and draw up a precise time classification that allows you to see if the case-back of your 16660 is correct and corresponding to the case serial number.
Let’s start.
IF the serial number is less than 6.6 million the only correct EXTERNAL-INTERNAL caseback combination is the following :
IF the serial number is between 7.3 and 7.5, the correct EXTERNAL-INTERNAL caseback combinations are the following :
IF the serial number is between 8.0 and 8.5, the correct EXTERNAL-INTERNAL caseback combinations are the following :
IF the serial number is between 8.5 and R5, the correct EXTERNAL-INTERNAL caseback combinations are the following :
SUPPLY CASEBACKS
For the replacement of casebacks prior to the end of the production of 16660, it is assumed that the temporally subsequent casebacks were used for the replacements.
The caseback that we are now going to explore was produced in the moment when the production of 16660 reference ended and it is what is officially considered as the service caseback.
Characteristic :
– There are two “Crowns” located between the words “Rolex” and “Original” and “Oyster” and “Valve”.
– The word “Original” is present before the writing “Gas Escape Valve”.
– The word PATENTED inside the case back is not present.
– The “G” of “Gas” has a more closed and rounded shape than the production series.
– The wording “ROLEX SA” is present.
– The graphics of the internal caseback completely differ from the production series.
