Not sure there's any specific symbolism to go with Be. More's the like it's enough to recognize it as an atom, but few enough to not cost too much for the design.
The whole coin thing is relatively new, started with the Army. Now the whole military gives them out. I have a few from the USAF for projects I've worked on over the years. I guess they are kinda neat-o, but you know... the life of a Nuke is doing more than the Coner's/topsiders (non-nuclear trained folks on submarines and targets respectively) and getting half the respect. When I was in it was not uncommon for Cones to get commendations and awards for simply doing their jobs, Nukes "need not apply" as the old saying goes.
Oh, and congrats to your boy. Now tell him to get hot, he's Dink.
