Clive -- isn't it "numismatics"?
The terms Clive suggests might well be exactly what the original poster was looking for. However, I just want to point out that they mean "collection" as in "the act or the hobby of collecting," not the actual collection of items that you keep in a desk drawer. If you just asked someone to define "philately" they would probably say "stamp collecting," not "stamp collection." (As in, "My hobby is philately/stamp collecting.") If you want to refer to the actual physical collection (as in, "Would you like to come inside and see my stamp collection?") you cannot substitute "philately."