Do electromagnetic shielding stickers do anything?
I call quackery. You don't want to shield the electromagnetic field, because that's what makes the phone work. If you would stop the EM field you wouldn't have communication.  

The "24 carat gold" should also ring a bell. I bet there's not a \$\mu\$g gold in it. Even if you want to make a shield there are much cheaper materials which perform almost as well as gold does, aluminium for instance. Despite what some people think you don't need a magnetic material like steel (iron) to shield off alternating electromagnetic fields. (Besides, gold isn't magnetic either.) For shielding you need a good conductor. Gold is one, but so are copper and aluminium. The magnetic field passing the shield creates eddy currents which in turn create a field countering the first one.