The Glycine caliber GL224 is a Swiss made automatic watch movement. As of 2016, Glycine Watch SA is owned by Invicta Watch Group.
ETA or Sellita Base:
The early Glycine caliber GL224 movement was based on the ETA caliber 2824-2. There may still be some of the ETA pieces out in the wild, but most of the newer GL224 powered watches available are based on the Sellita SW 200-1.
The movement pictured above is an earlier caliber GL 224 based on the ETA caliber 2824-2 with a custom branded Glycine rotor. This example was found in a pre-Invicta F104 watch.
Pictured below is an example of a GL224 based on a Sellita caliber SW200-1 with a custom rotor. The image was submitted by Brad (from the comment section of this post) of the movement found in his Glycine Combat watch.
How do I know which movement is in my watch?
Throughout the official Glycine documentation and technical data, they only refer to the caliber GL224 as a Swiss automatic movement. ETA and Sellita both engrave their logo and caliber number below the balance wheel, however, the easiest way to tell if your Glycine watch has the ETA or Sellita is by the jewel count on the rotor. If your GL224 powered watch has the ETA 2824-2, it will say 25 jewels. If your watch has the Sellita caliber SW200-1, the jewel count will be 26.
Why are they the same caliber number?
Glycine is currently owned by Invicta watch Group, which has been known to change base calibers in their watches while maintaining the same caliber number. Even though the SW200-1 is a clone of the 2824-2, they are not the same movement. For that reason, it would be beneficial to the watch community if they identified the movements with different caliber numbers, or at least added an indicator such as GL224-2. Since the GL224 can be either an ETA or Sellita, you might not know which you are getting, especially from sellers that don’t show the back of the watch.
GL 224 or GL224?
The official Glycine documentation refers to this caliber as GL224 without a space, but as you can see in the ETA powered movement at the top of this post, the rotor is engraved: Cal. No GL 224, with a space. The Sellita based image submitted by Brad is engraved: Cal. No GL224, without a space.
It’s possible that Glycine got rid of the space when they switched from the 2824-2 to the SW200-1, but this is doubtful because datasheets of older models powered by the 2824-2 were written the same way (GL224), despite the rotor having GL 224. Glycine provides limited documentation and images on their official website. If you have a 25 jewels ETA based GL224, please comment below if the caliber number on your rotor has a space or not.
Examples of watches with this movement:
Below is an ETA 2824-2 based GL224 movement found in a pre-Invicta Glycine F-104.
Invicta Glycine Combat Subs with the caliber GL224:
Click here for the official spec sheet from Glycine