Seamaster De Ville Case Manufacturer

Posts
1,582
Likes
2,696
Hello everyone,

Does anyone know the case manufacturer that matches this symbol?



I was aware that companies like Ross, Dennison, and Centrale Boites all manufactured cases for De Villes, but I haven't heard the name of the company whose hallmark is the triangle with a circle on top.
 
Posts
13,485
Likes
31,790
That is the mark for Ervin Piquerez S.A., Bassecourt, Switzerland.