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 Post subject: Gruen Wristwatch Case Serial Numbers. Gruen, Keystone, Star
PostPosted: Wed Nov 30, 2016 1:23 pm 
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I’m happy to be able to announce some initial results from the Gruen wristwatches case serial number dating effort.

I chose 3 different case manufacturers for this initial data set. They are Gruen, Keystone, and Star. This is FAR from complete. But I thought it could be useful to give this information to the Gruen Community because we can never have enough tools to help in the identification process and I have a relatively high confidence in the data in this table.

The way you read case serial numbers is by parsing a prefix of 2 or 3 characters (may be numbers or a combination of numbers and letters).

Projects such as these are rarely completed by a single individual and this project has required 1,000s of watches to be examined over a number of years. I would like to thank Barry "Bazzab" Cooper, Bernd "Barney" Riemann, and Cathy Orbista for their significant contributions to the project.

This project is FAR from being "complete". There are other prefixes still being decoded for the Gruen made cases for example. The Star cases also have many more serial number prefixes that will be published soon (hopefully).

Please feel free to comment and send me feedback as this is an active project and will be refined over time.

You can find the latest version of this table and other serial number tables on the GruenWristwatches site's Serial Numbers page.

Stay tuned…. more to come!
Code:
+----------+----------+----------+-------------------+----------+-----------------+----------+
|          | Gruen    | Gruen    | Gruen             | Gruen    | Keystone        | Star     |
| Year     | Prefix 4 | Prefix 5 | Prefix B          | Prefix C | Prefix K        | Prefix 0 |
+----------+----------+----------+-------------------+----------+-----------------+----------+
|          |          |          |                   |          |                 |          |
| 1940     |          |          |                   |          |                 |          |
| 1941     | 42 43    |          |                   |          |                 |          |
| 1942     | 44 45    |          |                   |          |                 |          |
| 1943     |          |          |                   |          |                 |          |
| 1944     | 46       |          |                   |          |                 |          |
| 1945     | 47       | 56       |                   |          |                 |          |
| 1946     |          | 59       |                   |          |                 |          |
| 1947     |          |          | B2 B3 B4 B5 B6 B7 |          | K10 K11 K12 K13 | 036      |
| 1948     |          |          | B8                |          | K14 K15         |          |
| 1949     |          |          | B9                | C1       | K16             |          |
| 1950     |          |          |                   | C2       |                 | 045-053  |
| 1951     |          |          |                   | C4       |                 | 058      |
| 1952     |          |          |                   | C5       |                 |          |
| 1953     |          |          |                   | C7       |                 |          |
| 1954     |          |          |                   | C9       |                 |          |
+----------+----------+----------+-------------------+----------+-----------------+----------+

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 Post subject: Re: Gruen Wristwatch Case Serial Numbers. Gruen, Keystone, S
PostPosted: Sat Dec 03, 2016 12:12 pm 
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Joined: Mon Mar 05, 2012 11:55 am
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Let me break into the lively discussion here for an observation ... ;)

As much as I like Style Numbers, these Case Serial Numbers are MUCH accurate. First off, they give you the TRUE manufacture date for the watch in hand. Second, you get around the perky Style Number re-use problem. The Case Serial Number will erase that problem, if your case is one of the solved series. I'm working hard to solve more of the manufacturers in this post, along with others not yet published.

I hope to get a "Calculator" running soon on the GruenWristwatches site that, like the Style Number Calculator, will provide a date given a Serial Number. I'll also be adding a bit of verbiage to the Identify Your Gruen tutorial that works in how to use these new tables.

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 Post subject: Re: Gruen Wristwatch Case Serial Numbers. Gruen, Keystone, S
PostPosted: Sun Dec 04, 2016 1:11 pm 
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A few more interesting facts are emerging from the data as I work on the calculator code....

We know Gruen placed quite a bit of importance on case serial numbers because it is the single common bit of data found on dealer's invoices and in the packaging of the watch itself. It seems like the case serial number is how Gruen tracked each individual watch. And this makes sense, right? It's a POTENTIALLY unique number that can identify a specific watch and it's easy to locate and read.

If the Case Serial Number is really meant to be unique, then there needs to be coordination on the numbering scheme across all case manufacturers. Given how confusing the 405 series movement serial numbers are and how Style Numbers were rampantly reused, I had little faith that Gruen was going to get this Case Serial Number thing correct.

But, the data is starting to show that Gruen was in fact on top of the Case Serial Numbers. Case in point.... Wadsworth serial numbers versus Gruen made case serial numbers.

The early Wadsworth cases have been decoded to be:
Prefix Code Year
50 1925
51 1926
52 1927
52 1928
53 1929
54 1930

These serial numbers were all totaled 7 digits in length.

What about the Gruen made cases? There are Gruen serial numbers that start with "5" too.
What the data is showing is that Gruen made cases also have 7 digits in length, but the lowest prefixes are "55", right where the Wadsworth cases stopped.

Other case manufacturers have letter prefixes just like the Gruen made cases did. But in these situations Gruen chose to use differing lengths of serial numbers to distinguish them.
One example is the Pioneer made cases. There are Pioneer cases that begin with a "5". BUT, Pioneer cases I've seen so far have a total of 6 digits, not 7 like Wadsworth and Gruen cases.

It's too bad we don't have the cheat sheet for these case serial numbers.... or if one exists it hasn't been made public. But I think now that it is possible to reverse engineer a great number of them. Time and effort will tell the tale in the end and I think it's an effort worth spending time to solve. We have the potential to date ALL Gruen watches someday using the case serial number and that's an exciting possibility! I don't think anyone would have said something like that 10 years ago, but the landscape of Gruen research has changed in the past decade and I see a lot more changes ahead as these and other problems are solved.

I will certainly keep everyone, interested or not, up to date on the development of the Case Serial Number Dating Tool, I think I'll have one done pretty quickly containing all of the data that's been presented so far with hopefully some additional findings.

If anyone has suggestions on priorities I'm interested in hearing back what manufacturers or series is most important to you.

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 Post subject: Re: Gruen Wristwatch Case Serial Numbers. Gruen, Keystone, S
PostPosted: Sun Dec 04, 2016 3:39 pm 
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Hi Mike,

this is great work, I will find it personally useful - so thanks! It's also good to see you post again after what feelsl ike such a long time since you closed your forum.

Kris.

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 Post subject: Re: Gruen Wristwatch Case Serial Numbers. Gruen, Keystone, S
PostPosted: Mon Dec 05, 2016 10:37 am 
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Been right here... haven't gone anywhere. Maybe you've missed some of my posts? It's been 4 years since the forum. Lots of stuff since then including several books. I took a bit of a break this summer after the big push to complete my last book, The Gruen Watch Catalog.

I'm always simmering some kind of research in the background. The problems are interesting and challenging. It's fun to be able to fill in some of the puzzle pieces and supply newcomers with tools we all wish we had when we started.

Glad to hear you'll be using the work we completed.

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 Post subject: Re: Gruen Wristwatch Case Serial Numbers. Gruen, Keystone, S
PostPosted: Tue Dec 06, 2016 7:29 pm 
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Joined: Thu Nov 15, 2012 4:23 pm
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Location: Ontario
Well done Mike! Looking forward to seeing some more of your work.

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