Magneto Master of Diamagnetism?

Is magneto the master of magnetism, or the master of "i can do that" most specifically does he have the power of Diamagnetism. and if so why is it so limited.

ok backstory, The original premise I thought of when I was introduced to the character of Magneto is that He can effect anything with Iron in it. As I grew older I learned that magnets effect more than just iron, but Cobalt, Nickel and to a lesser extent Aluminum. (I will assume that adamantium and vibranium are effected since they are made up) But I continuously see Magneto messing with objects that clearly do not contain those items. most notably modern tooth fillings which would be MRI safe utilizing either gold or Titanium , or I see him stopping bullets constantly and crushing that brass bell in the movie. you could argue that the bullets are lined or cased in steel as is sometimes done particularly with some armor piercing rounds. but this is rarely the case and for a man that just kind of stands there when someone points a gun at him, he would be taking a big risk if he couldn't maniopulate lead SO. the theory is, Magneto is the Master of Diamagnetism as well and Ferrousmagnetism which would allow him to mess with Bismouth, gold, silver, and mercury as well as a specific carbon and a superconductor. but he would have to exert his power Immensely to effect Lead at all since diamagnetism is such a weak force and weaker still on materials not listed above. so presumably more so to be able to stop such a strong force as being fired from a gun, which would mean he should also be able to control, diamonds,copper, water, plastics, rubber, and the whole list of things not effected my magnets as ALL things are susceptible diamagnetism at least weakly (around as weak as lead) which further complicates things, as he specifically cannot control those things.

SOO.. my question, does magneto just have ultimately ambiguous powers that he himself doesn't understand? does he have more power than he leads us to believe? or do the writers just need to go back elementary school where we all learn about magnets and magnetism?

Read this: Magneto power

wow, good read, thank you @cheesesticks I guess Master of Magnetism sounds better than Master of I Can Do That, and when writers depower him to not effecting plastics (or that futuristic Sentinel of alternative materials that he couldn't control) i guess Its more a case of the writer not understanding the character.

@bierschneeman: Yes i agree, Magneto can affect a lot more things than metal. If every writer would write Magneto at his real potential he would probably be stomping everyone. Take a look at some Magneto feats, it's incredible how he can be powerful. I'm happy to find another Magneto fan!