How Do I Turn In Someone Selling Counterfeit Tiffany & Co. Jewelry?

I know of this woman in my town who is openly selling fake Tiffany jewelry. This disgusts me because I’m a long time customer of Tiffany and it makes me embarassed to wear the real thing.
I just think it’s ridiculous that a grown woman would do this.
I want to turn her in to the police, but I’m afraid.
Any suggestions?