Up for sale is this rare SEIKO 6105 8110 Proof/Proof diver watch. At first glance it may look like an ordinary 6105 with different text on the dial. But once you have one in your hands you can clearly see more subtle design differences.
Beside that, the Seiko 6105 is a real iconic diver watch in the SEIKO history. The 6105 has earned a legendary status among collectors due to it's groundbreaking asymmetric case design, quality that rivaled Rolex and Omega dive watches, and it's provenance as the go-to watch for those who served in the jungles of Vietnam in the late 60's, early 1970's.

The watch for sale is a 1st gen. prototype of the first series from mid 1970, which was only produced for a very short period of 3 months (May, June, July). Then SEIKO removed the "Proof" text and started using "Resist" leaving these early examples to be quite rare and special. But it's not only about the text. The watch shows some more essential differences to the later manufactured watches, so that these early examples are quite rare and special. For all those interested, please take the time to read the detailed description below, which documents the specialty of those early SEIKO 6105 8110 divers.

The watch is 100% original SEIKO. Everything works as it should. It runs great and was overhauled by a watchmaker last year. The second hand has been replaced with an original old one.
The bezel rotates well and engages perfectly. The crown locks perfect. The date switches cleanly and the movement runs good, keeping the time properly.
Overall, the watch is in excellent used condition, showing the normal signs of age and wear of a 50-year-old watch.

So, what this means is you have the opportunity to acquire a very rare specimen indeed. And this one is quite nice.

Reflecting the rarity, price is set to 3250 Euro. Recently a ebay listing for such a watch ended with a price of 5200 USD. (check here: https://www.ebay.com/itm/203300682331?hash=item2f55aa3a5b%3Ag%3AG0AAAOSw55NgSA2e&mkcid=1&mkrid=707-53477-19255-0&siteid=77&campid=5338673736&toolid=20008&mkevt=1&nma=true&si=j99On%252BRu8p42bMLmQMEugmZikP0%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

The watch is located in Italy. You can contact me at alexblex@gmail.com

We all know that prices on these fantastic vintage Seiko's have gone up a lot in the past years. This is a nice opportunity to own one.
Thanks for looking. Kind regards, Alex

The watches of the first 6105-8110 batch production series (from may, june, july 1970) differ in the dial, case, caseback and crown. Both the dial and the caseback show the words "Proof" instead of "Resist" they used later. The case is also thinner than the "Resist" version. The crown is also designed differently. These features can only be found on the early examples of the Seiko 6105 8110 range.
The differences in detail:

Dial: text “WATER 150m PROOF”, also matt, non-polished indices. The dial code is: JAPAN 6105 8000T

Case: In short, the later „resist“ cases are thicker and clunkier. The proof case is noticeably thinner and therefore looks more elegant.
The Seiko 6105-8110 was the first Seiko diving watch with the characteristic asymmetrical case shape. This makes it very comfortable to wear, also because it is so thin - the proof case is even thinner. In addition, the crown area is much more rounded and thinner. You can see that especially in the very elegant crown protection lines, which in comparison with the resist case looks simply blockier. With the „resist“ cases used later, the lines of the crown recess are much straighter. The lugs of the proof case are also tapered and more streamlined. The fall lines are noticeably thinner and more streamlined compared to the resist case. The lugs on later resist cases are much thicker and blockier, I would call them "shoulder-shaped". If you have watches with both case shapes at hand and you compare them with one another, the differences are very noticeable. The 6105-8110 Proof / Proof definitely looks a lot slimmer and more elegant.

Back cover: The so-called “Horseshoe” inscription with 6105 8110, “Water Proof”, serial number from May, June or July 1970.

Crown: 6 grooves for each of the 6 sections. Later, the crown was changed and made with 7 grooves, and over the years they changed it again to 8 grooves.

Movement: Early version of the 6105 movement with bevelled edges. With second stop, of course.

Hands: Mainly the Proof/Proof unse a long second hand. In this watch the second hand was replaced with a original Seiko 6105 second hand.

My watch for sale is unpolished and of course has age-typical signs of wear on the case, bezel, but nothing dramatic. The case back shows signs of opening. Look at the photos. In real life, the watch looks much better than on these macro photos!
I tried to capture the state as well as possible. Please look carefully at the pictures. For the pictures, I only took the watch out of the storage box and photographed it with my smartphone. So it's not for aesthetes, but honestly anyway. Nothing has been specially polished, so you may also see dust particles and streaks from touching or reflections from lightning.

Just for showing a recently sold example: