A 2013 prototype of the Apple Watch

Seen on 9to5Mac, photos of a 2013 Apple Watch prototype.

The article explains that the sensor is different from the final version, as well as the decoration of the crown. It also shows that the markings are specific to this model, and the watch runs on a test OS. Finally, the charger is proprietary and only works with this model (it cannot charge any other Apple Watch).