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SEIKO 6105-8110 150m Diver PROOF
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Discussion Starter · #1 ·
R and T

I read a discussion in this forum about vintage Seiko lumes. It led to Radium vs Tritium lume hypothesis because there is R vs T dial code, respectively.

But I saw that the R and T dial codes can be found on almost all vintage Seikos and modern Seiko regardless of whether the dial has lume or not. So it goes without saying that it is not the code for lume material.

After some quick Google Image research and also looking back at my watch photo archives, I found out that most of the R dials are on vintage Daini Seikosha watches (44KS, 52KS, cal. 7017) and most of the T dials are on Suwa Seikosha watches (cal. 4005, 4006, 6139, 6105). This leads to my hypothesis that the dial code is indicator for the factory that supplied the dials. R by Daini and T by Suwa.

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King Seiko 44-9990 (Daini) with R dial code. Photo credit to: Seiko's Affinity to Hi-Beat Movement - Part Two - Monochrome Watches

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Seiko 6105-8110 (Suwa) with T dial code.

Those who did their research on the 6309 divers will remember the "CASED HONG KONG" dial code that indicates where the watch was assembled. So it is safe to say that the R and T codes are also related with location or, more specifically, the dial factory in this hypothesis.

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Seiko 6309-7049 (Suwa), T dial code, cased in Hong Kong.

But we know there are some anomalies such as ref. 6139-6002 (Suwa watch) with R dial code (Daini dial, assuming that my hypothesis is valid). The 45 King Seikos (Daini) are also all marked with T code (Suwa dials). In this case, I assume both companies shared their production facilities. This is a well known fact among vintage Seiko collectors because we also found some 6217 (Suwa) and 6139 (Suwa) with Daini Seikosha marking on the rotors.


"Pointy A" and "Flat A"

Further observation tells us that the R code always comes with "pointy A" JAPAN and T code with "flat A". It is so consistent across all models and period that it looks like there is an agreement between Daini and Suwa factory to keep this little details. Surprisingly, they are still holding the tradition until now.

I just checked my Grand Seiko pictures and found out that the modern SBGA011 "Snowflake" and SBGV009, both by EPSON or previously known as Seiko Time Corp/Suwa Seikosha, still has the same T dial code and "flat A" JAPAN.

My modern SBGW033 and SBGW047 that made by the Shizukuishi studio (previously Daini Seikosha) also still have the same R dial code and "pointy A" JAPAN, just like the old times.

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Grand Seiko SBGA011 "Snowflake", EPSON (previously Suwa Seikosha), T dial code and "flat A" JAPAN. Photo credit to: Review: Grand Seiko Spring Drive SBGA011 "Snowflake" -

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Grand Seiko SBGW047, Shizukuishi studio (Daini Seikosha), R dial code and "pointy A" JAPAN.


S Dial Code?

Beside the R and T, I also found the S dial code on my 7017-8010 "Pulsimeter" and 7016-8000. They are both Daini Seikosha watches. Who made this S dial? It has "flat A" JAPAN that relates it to Suwa factory. Why not T if it was from Suwa? Is it a third supplier? Let me know what you think.

Regards,
Indera


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Seiko 7016-8000 (Daini Seikosha), S dial code, "flat A" JAPAN.

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Seiko 7017-8010 "Pulsimeter" (Daini Seikosha), S dial code, "flat A" JAPAN.
 

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Great thread and amazing research here.

Regarding "Pointy A" and "Flat A" as it relates to Daini and Suwa.
"Further observation tells us that the R code always comes with "pointy A" JAPAN and T code with "flat A". It is so consistent across all models and period that it looks like there is an agreement between Daini and Suwa factory to keep this little details. Surprisingly, they are still holding the tradition until now."

I did find some anomalies with this observation in that the 7002-700X and 6309-729X divers that have R code dials and "Flat A" in JAPAN in both examples, meanwhile, 7002's have Daini logos in the dial codes while 6309's have Suwa logos in the dial codes:

6309-729X



7002-700X


 

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SEIKO 6105-8110 150m Diver PROOF
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Discussion Starter · #3 ·
Thanks for the anomalies, Rainier. As they said, a theory is only valid until it is proven wrong. 😄

I missed out on the slim case 6309-729x and 7002 divers. This must be a very turbulent period in Seiko watchmaking business because the dial code has many variant and for the first time we see the "SINGAPORE" dials that marked the start of production in Singapore factory.

I also checked photo of the 7002-7039 "Transitional" which has 200m marking and this particular model follows the R and "pointy A" theory.

Nice info. Looking forward to more anomalies.

Regards,
Indera

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Great thread and amazing research here.

Regarding "Pointy A" and "Flat A" as it relates to Daini and Suwa.
"Further observation tells us that the R code always comes with "pointy A" JAPAN and T code with "flat A". It is so consistent across all models and period that it looks like there is an agreement between Daini and Suwa factory to keep this little details. Surprisingly, they are still holding the tradition until now."

I did find some anomalies with this observation in that the 7002-700X and 6309-729X divers that have R code dials and "Flat A" in JAPAN in both examples, meanwhile, 7002's have Daini logos in the dial codes while 6309's have Suwa logos in the dial codes:

6309-729X



7002-700X


 

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Interesting theory.
One thing to add is that the 6139, specifically the 6139-600x are known to have both T and R dial with the characteristics you mentioned above.

However the early North American Resist models (6139-6005/9) also known to have Daini rotor and caseback but mostly comes with T dial. It is not known though to what extent Daini produce the parts or assemble the watch.
 
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