Submarine Badge

[uscob]

As everybody knows, the Dress Regulation shows the golden Badge with a Submarine.
Now I have some in bronze and silver, so 3 different colours.
Does anybody knows what these are for?
Maybe to expensive for a mistake to make them.
Don't have them by the Hand right now but I think to remember that these are Assmann Badges.

[Nightwish]

Possibly to differ times of Service?

[uscob]

37/10 say's it has to be gold and the new Regulation states that it has to be awarded after a succesfull 6-Month Course Time on Board.
Nothing about the 2 other colours.