How Do I Tell Her To Stop Staring At Me Without Being Offensive?

I work with this woman who comes into the office and stands there to talk to me. During the entire time she stares at me. When the conversation is over she stays there and keeps staring. It's like "go away!". I can't stand it. I tried staring back but that was too awkward. It kills me and makes my anxiety go through the roof. What do I say or do to get her to take the hint and stop staring? (without being rude)