Thanks for visiting my vintage Hamilton watch blog. I like to restore US-made Hamilton wrist watches back to their original glory and share my experiences with other enthusiasts. Use the "Search" space below if you know what model you're looking for. Feel free to leave polite comments or questions in the spaces provided. Also check out my "watches for sale" on my Etsy site - the link is on the right, just below.

Thursday, November 21, 2013

1954 Automatic K-300 CLD

Automatic movements are self-winding movements that wind as you wear them.  You can also wind them manually by the crown, like a mechanical watch.  Some Swiss makers introduced automatics in the 1930's  but Hamilton didn't introduce them until 1954, when they added the 12 new models - including their first calendar watch too.

One of the 1954 watches was the Automatic K-300 CLD.  The CLD line was "sealed" with a series of gaskets around the various seams… bezel, crystal, crown, etc.  They weren't waterproof, just sealed from the environment in general.  The K-300 was only available for two years.

The new models introduced a numerical nomenclature that is defined by the case material.  A 100-series watch is 18K gold, 200- is 14K, 300- is 10K, 400- is gold filled and 500- is stainless steel.  Eventually there were even 600-series watches with rolled gold plate.

So with that in mind, you should know that the K-300 has a 10K solid gold case.  Like a lot of 1950's watches, the decorative lugs have a funky shape.  The silver dial features solid 18K numerals and markers with pearlised dots.

I recently purchased a K-300 but I had to return it.  I'll tell you why a little later.  As received it was in very nice shape but it had a smudge across the top of the dial.  I had hoped to be able to clean it off.

Most CLD watches have two-piece cases where the movement is held in the case back and the bezel pops off the front.  But the K-300 has a pop-off back and the movement is held in the front.

And here's the movement.  This is a very interesting movement.  In fact, it was only used in the first automatics.  There's no Hamilton number associated with it - it just says "Hamilton" on it.  I had to do quite a bit of research to figure out what it is.

It's called an Eterna-matic.

Eterna-matics are made by Eterna, a Swiss watch company.  They introduced automatics in the 1930's and their trademark is the 5 ball bearings in the center of the rotor.  You can see them in the photo above.  Those five ball bearings dramatically reduce the friction of the rotor and they became the logo of Eterna as well.  Eterna also introduced a subsidiary, ETA - which is the maker of Hamilton movements today.  Small world, huh?

So why did I return the watch?  Well, I couldn't get the movement out of the case!  It needed to be serviced but it would not budge for me.  Others had tried before me, you can see some pry marks on the movement ring near the lugs.  I was really bummed to return it but I was afraid I might damage it if I tried any harder to get it out.  Goofing up an Eterna-matic would be a costly mistake for sure.  Any other automatic, no problem - but try finding a loose Eterna-matic.

I suspect the gaskets around the movement ring must have hardened to the point they were a solid mass.    You'd probably have to dig the gaskets out with a pick to free them up… or maybe soak them with something.  Beats me.  Returning it was the best option.

Oddly enough, I know the person who bought it after me and I helped them send it to a professional watchmaker for service.  I'm really curious to see how it turned out because it's a very nice and uncommon model.

I also want to know how they got the movement out!


Turns out there's not much of a mystery.  Once the stem is removed the movement and movement ring come out the back with a little persuasion.  One option is to remove the crystal and push on the dial.


  1. I've been trying to identify the movement caliber in a Hamilton K200, the K300 looks exactly the same, very surprised to learn that it is an Eterna-matic.

  2. Did you ever find out if and how the movement was removed from the case? Is this an issue for regular USA Hamilton CLD's.

    1. Yes - the movement and movement ring come out the back. This one was just stuck in there and needed some persuasion. Any movement held in the case by a movement ring and gasket can get stuck but they normally are easy to remove. This one was stuck a little more solidly, that's all.

  3. According to you, the first digit is the bezel material, and the second is the case back material. If the second digit in K-350 is a five and that means stainless steel, what might the first zero in the K-300 mean? And I also assume that the last digit is to tell which model it is, such as, the first or the second or the third and so on?

    1. There are exceptions to every rule but if the 2nd digit is a 5 then it has a stainless back. The first digit is the case material. The 3rd digit is used relative to the 2nd digit...01,02,03, etc.

  4. I recently got a cheap franken-cased watch and based on your photos of the dial it looks like this is what it started out as, I guess someone scraped out the gold case at some point. it's an oddball to look at with that dial and hands in an oversize 70s stainless steel diver style case but it's running great.

  5. Dan, what would a pristine k100 original opener all boxes be worth today. I have seen many k models for sale but never k100.s on only your site what is your opinion.Thanks Dan for all of your knowledge paul

    1. Tough to say, you don't see them very often. If it's really pristine $800 isn't unrealistic... it's solid 18K after all. That said, an 18K Astramatic would be more interesting... you never see those for sale. For both models the old adage applies, "Try to find another".