Frankenstein's watch? Seiko KS or GS?

A sentimental favorite among my watches is one that I got from a bazaar in Tokyo almost a decade ago for 5,000 yen. It was more expensive than the Swatch watches I got brand new from stores in Akihabara and Okachimachi. I was in Japan then as a visiting scientist and I think I was reliving my student days during the 1990s when we frequented bazaars to get some nice items without shelling out a fortune. The design was simple enough for me and it was a Seiko automatic watch so you really couldn't go wrong here. I had a reliable Seiko quartz that looked like this one back when I was in high school and I got my self a couple of Seiko Kinetic watches including the titanium watch I usually prefer over all my watches (including my Baume and Omega).

An old Seiko automatic watch is not as simple as it seemed.

I didn't mind the KS mark on the watch face. The thing that got my attention was the kanji day indicator. The kanji in the photo is for suiyobi or Wednesday.

The shape of the watch was also a classic and reminded one of the Rolex oyster

Only about recently have I discovered something about the watch as an acquaintance casually mentioned that this was a collectible watch. KS stood for King Seiko, which was a predecessor of sorts of the Grand Seiko watches I thought were quite expensive considering (sorry Seiko) they weren't a Swiss brand. It turns out the Grand Seikos and the King Seikos were masterpieces in their own right and were advanced and quite accurate for automatic watches compared to their Swiss counterparts.

The back was also different from my other Seikos in that there is a brass plate. The watch model is stated as a 5646 7010.

Some internet research told me that the watch model was stated at the back and front (fine print at 6 o'clock). The back of the watch states that this was a 5646 7010. However, as it turns out, this model did not correspond to a King Seiko (KS) but to a Grand Seiko, and should have GS in the plate. Inspection of the front revealed another model 5626 7040, which corresponded to a King Seiko model.

The watch model stated in the face was different from the one stated at the back. It showed that this was supposed to be a 5626 7040.

And so I suspected that this was a fake watch given the conflicting labels. Further research though got me intrigued since the face of the watch was that of a 5646 7010 with GS instead of KS prominent above 6 o'clock. A KS 5626 7040's face stated chronometer and the indices were significantly different from this one's.

Etched inside the back cover is the model number

I realized that instead of being a fake watch, this could be one that was modified or tinkered with. That made more sense given Seiko watches are popularly modified for them to look like other watches but using components that the modifier liked in order to come up with a customized watch with his/her preferred features. The clincher had to be the movement, which was the heart and soul of the watch. And so I opened the watch to see what was inside.

Opening the watch revealed a genuine movement by Seiko.

This was a 5626 B movement

The 25 jewels and 5626 B was an upgrade to the 5626 A movement that the King Seiko of that model series first used. I also learned that this was practically the same as the 5646 movement used by the Grand Seiko.

I learned that the 5626 B was "chronometer-grade" 28,800 beats per hour. My curiosity led me to compare this watch's time with those of my other watches (the Kinetic, which has a quartz movement and my automatic Baume that was at 28,800 bph) and I concluded that it kept really good time. 

And so this is quite a complicated watch in the sense that it has the movement of a KS (5626 B that's practically a GS 5646 movement), the back of a GS 5646 7010, the face of a 5646 7010 (which is also very similar to a KS 5626 7113), and the body of the GS 5646 7010 (that also similar to that of a KS 5626 7113). No matter, I'll be using this mutant of sorts and cherishing it as a souvenir from my years of staying in Japan. 

[Note: I tried the online Seiko Production Date Calculator and it estimates the KS 5626 7040 with serial number 090502 to have been manufactured in September 1970. 7/19/2018]

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