All about Gruen

[Mr. Bieser]

Another example of known source and cal designation, circa 1912- but unknown Gruen caliber number.

This is Aegler 21.

(Thanks Barney for your research and sending this)

This one is somewhat similar to Gruen calibre 812 & 820, and others around the early 800 blocks.

But again, Gruen calibre: Unknown. Only a number but means a lot.

[Fred]

Yours appears to be a larger variant—is it 13L, like the later 870/871? The case has a man’s styling IMO and is pocket watch, so just guessing size.

Here is another size variant of this layout—a tiny wristlet that wouldn’t be a practical pocket watch. Sharing, in case it is known. But yours is the true match to #21.

The Aegler caliber number pairs I haven’t matched yet.. one of these? I note 808-9 are 7J but they are 10.5L and might match 806-7.

800-1
808-9 - 10.5L
810-1
(812-3 seen with Premo branding)
814-15
816 - 10.5L

[Mr. Bieser]

Apologies for bad pic & the bare bones data, I'll supplement better info as time allows.

The one you are showing, would certainly be a Gruen Caliber 820, if it had different branding.

Mine is small too, it's a ladies pocket watch in a gunmetal Premo Suisse case. I estimate it to be about 11 ligne.
And it runs.

[Fred]

Here is # 21 in rare Hunter 7J under Rebberg Watch Co branding for US market. This US launch happened in 1914. Same timeframe as Premo in market. https://www.ebay.com/itm/124933522263

28.83mm case diameter here, so your 11L seems right. I suppose it could be up to 11.75L movement.

[Mr. Bieser]

Thanks for the link, looks like it, interesting find for sure.
The one other instance I've seen this branded Premo calibre in use was in a Premo marked Modish style sterling wristlet.

[Fred]

This one has me piqued, for sure. I found 2 OF examples in my pics, both Premo. Pilot cases, but neither list the size or model #. Too old I guess.

-pilot 286k wire lug ladies (ceramic dial)
-pilot 290k convertible (gilt dial)

Kicking myself on that convertible. Came up last Christmas and wouldve had the caliber # on dial back. Rats

[Mr. Bieser]

While i didn't take the movement out of the case, used non digital calipers to measure, my updated *estimate* is that the movement is either 11.5 or 11.75 ligne.
The dial is ceramic.

[Fred]

Could this be the Rebberg 12 ligne offering? It existed, but none have been categorized visibly online. Just saying--there are other Rebberg calibers from this time in the 11 to 11.5 L space.

And I will speculate 12L must be the rarest of the Rebberg sizes. I see a mention in a 1998 NAWCC pub, but I am no longer a paying member to see if there is even a pic of the movement in the article. I've found this movement under at least 4 other brands now, but alas only as "sold."

You have, once again, found a juicy & tempting puzzle!

[Mr. Bieser]

I still estimate the movement to be 11.5 or 11.75 ligne.
25mm from here to there on redline.
Case is 30mm.

[Fred]

Very possible. Hoping we can verify one day!