Mystery of the Gruen watch
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Thread: Mystery of the Gruen watch

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  1. #1
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    Mystery of the Gruen watch

    A bit of back story: The Gruen watch in question was handed down to me as a token of some personal and sentimental reasons. This took place around 15 or 16 years ago. In the beginning of my ownership of it I didn't really put much thought into what it was or the age or origins of the piece. Since then, every few years I would get online and try to find some information on it, specifically the age, but all without much result. Fast forward to today. I just came across the gruenwristwatches.com dating literature. I have been able to determine that the caliber I have (No.115) was only utilized during one production year, specifically in watch style number 275. When you plug this information into their style number decoder, it comes up with a year of 1937. Fantastic! But now I have some more questions...

    1. The piece I have is marked 15 jewels but I have seen eBay listings of cal.115 movements with 17 jewels. Is it possible to have the same caliber with two jewel counts?
    2. I don't entirely believe that this dial and the movement are original to one another. Can someone shed some light onto this theory as to whether I am correct or not.
    3. This is obviously not the original case as the inside of the caseback is stamped "Duro watch case co." Does anyone have any interesting info on this case and/or company?

    As a side note, not knowing the age of the case, the 10k RGP is holding up fantastically well. In addition, the entire watch is showing very well. From the dial to the movement, etc. It has very clearly been well cared for prior to my ownership.

    I hope there are a few people that have more knowledge than I do on these watches and can help me in my journey to uncover it's story.

    Thank you!
    -M

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  2. #2
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    Re: Mystery of the Gruen watch

    Hi M,

    first of all: nice watch, I definitely like it!
    To answer your questions:
    Caliber 115 is more or less a family of movements base on the same design, they are called caliber 115, 1157, 1158 and 1159. Definitely most common are 115 and 1157. whereas 115 is the 15 jewel variant and 1157 is the 17 jewel variant. But both are marked 115 at the plate. The movement was one of the first made in the new Gruen Precision factory in 1925. The movement was used in many watches. but most style numbers were before 200 - so the style number decoder incorrectly shows the use of the movement for one watch only. There should be about 20 different models from Gruen using caliber 115 or 1157, one of them is the "Tank". The movemnt was in production until 1930, probably 1931. Your movement serial would date it to 1927 as far as I can tell.
    Like you already anticipated definitely the case is not original to the movement. Duro never was supplier to Gruen, they only made after market cases to recase older movements. The case is probably about 20 years younger, I would assume late 40s or early 50s. Duro and Sutton made many such cases for several older movement sizes.
    The dial might be original from a Tank and refinished later or less likely came with the case. I think that the gold figures are original to the Tank, too expensive for the recase.

    I also own a couple of these recased 20s movements, some in Duro cases which were sold for example at Swartchild. You can still buy these cases at ofrei.com today.

    Barney
    Last edited by Barney Green; 1 Week Ago at 17:28.
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  3. #3
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    Quote Originally Posted by Barney Green View Post
    Hi M,

    first of all: nice watch, I definitely like it!
    To answer your questions:
    Caliber 115 is more or less a family of movements base on the same design, they are called caliber 115, 1157, 1158 and 1159. Definitely most common are 115 and 1157. whereas 115 is the 15 jewel variant and 1157 is the 17 jewel variant. But both are marked 115 at the plate. The movement was one of the first made in the new Gruen Precision factory in 1925. The movement was used in many watches. but most style numbers were before 200 - so the style number decoder incorrectly shows the use of the movement for one watch only. There should be about 20 different models from Gruen using caliber 115 or 1157, one of them is the "Tank". The movemnt was in production until 1930, probably 1931. Your movement serial would date it to 1927 as far as I can tell.
    Definintely the case is not original to the movement. Duro never was supplier to Gruen, they only made after market cases to recase older movements. The case is probably about 20 years younger, I would assume late 40s or early 50s.
    The dial might be original from a Tank and refinished later or less likely came with the case. I think that the gold figures are original to the Tank, too expensive for the recase.

    I also own a couple of these recased 20s movements, some in Duro cases which were sold for axample at Swartchild. You can still buy these cases at ofrei.com today.

    Barney
    Barney,
    Thank you for the information! Its really thebfirs time I don't feel alone in the frustrating process of digging through a lot of confusing information surrounding Gruen watches. Since my earlier post, I also found where the 115 was introduced in 1925. I've also come to realize that the decoder I was using ranges the dates (by style number) from 1935 - 1956. Within that range, it only shows the 115 being used in style number 275, which according to that decoder, puts it at 1937. My theory of the dial not being original, stems from it not having "precision" printed on the dial. Your guess on the serial number is going to be far better than mine because I've always ready that Gruen S/N's were numbered without rhyme or reason. And finally, I never knew that Duro cases could still be had today!

    Thank you again for the information you've provided, very much appreciated!

    -M
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  5. #4
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    Re: Mystery of the Gruen watch

    M,

    at that time PRECISION stamping on the dial was related to 17jewel movements. Since yours is the 15 jewel version, it should originally not have been PRECISION stamped. So this is quite OK. Nevertheless the dial printing looks refinished. I think it is original but got a new printing somewhen in between production and now
    There is a sense in Gruen serial numbering but it is really a difficult pattern which is related to the production location.
    Although the Duro cases are still available today, they are NOS. Definitely not produced during the last 30 years, so they can be called vintage as well.

    Barney
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  6. #5
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    Quote Originally Posted by Barney Green View Post
    M,

    at that time PRECISION stamping on the dial was related to 17jewel movements. Since yours is the 15 jewel version, it should originally not have been PRECISION stamped. So this is quite OK. Nevertheless the dial printing looks refinished. I think it is original but got a new printing somewhen in between production and now
    There is a sense in Gruen serial numbering but it is really a difficult pattern which is related to the production location.
    Although the Duro cases are still available today, they are NOS. Definitely not produced during the last 30 years, so they can be called vintage as well.

    Barney
    Gotcha, so that's the mystery of the dial solved 😂
    I definitely feel better knowing more about this piece. The watch definitely still runs but I'm afraid to wind knowing that it hasn't been serviced in a loooong time. That's my next step.

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