The Alpina Gruen Guild was a union of watch and movement manufacturers.
1905 the North American watch manufacturers Gruen and Hamilton enter the Alpina - Union Horlogère. This leads to the formation of the Alpina Gruen Guild SA.
Well-known due to its unusual rectangular shaped case, the “Doctors Watch” was manufactured in the 1940s under the brand names Alpina, Gruen, Alpina Gruen Guild and Rolex (see also Rolex Prince).