If I am not mistaken I believe the swan is Swarovski Crystal. At least they are known for stamping the swan on their pieces. If I am correct then the C is copyright, and the other I cannot make out, it may be a stamp for the metal content.
I may be WAY off base, but that is all I can figure out. Also Many Swarvoski Pieces have a CIRCLE, the Cubes are less common. I know I have seen a few early pieces with the Cubed swan.
I hope I helped, I really dont know if I am even close to being right.