Transition Metal of the Week

Well I had a transition metal as my element of the week before, but I had to pick a different one to keep things interesting. So it's Cobalt. Number 27, abbreviated "Co" and the origin of the name is the German "Kobalt" meaning evil spirit. I thought that was very chinese medicin-ey! Cobalt is quite special, as it is one of three elements that produce a magnetic field. It's uses are magnets, ceramics and special glasses. And I got a nice definition of a transition metal -- they have valence electrons present in more than one shell so they can exhibit several common oxidation states. I'm thinking the oxidation states are why cobalt makes pretty colors in ceramics and glass? Because supposedly it is clear, but of course we all think of it as a gorgeous blue. If anyone knows if this is due to oxidation, please let me know.