In the scene where Dr. Octavius is first testing his fusion in front of the reporters, and the mini star starts sucking all things metal into it, there is a shot of Dr. Octavius's wife. If you look closely she is wearing earrings. When everyone else's jewelry is being sucked into the star, hers is keeping perfectly still.
I agree. I don't remember but in my science class I think my teacher said that only Iron, Cobalt and Nickel were attracted by metal. I wasn't really paying attention, but oh if my science teacher is reading I was really paying attention, but the earings could have been made of some other material.