My $.05:
-Don't forget the thickness of the hub- like the hub diameter and keyway size, the hub thickness would be the next most standard measurement to specify a certain manufacturer since they have to be interchangeable on different parts of the geartrain.
-Then the material (cast iron, steel, Zamak(Atlas for instance))
-Also take a pic of one and try the google picture recognition search if it has any other distinguishing features.
-ALSO- if you have three gears that look like the same manufacturer, with say: 24, 48, 56, 37, teeth, then Google "lathe change gear 24 48 56 37", since certain companies offered certain mixes of different #'s of gear teeth. I threw "37" in there to make it more obvious, since that is a weird number.
-Google the number of gear teeth at the same time as any number stamped on it.
Bernie