why can't I mail cloisonne Christmas ornaments to America?

I've just now gone to the China Post Office here in Beijing to mail 20 cloisonne Christmas ornaments to my friend in America. I've done that for more than five years. But this year, the clerk refused to allow me to send it. She said it's a prohibited item. I can't find the law about that. These ornaments are not cultural relics. They're cheap souvenirs. Do you know if there is a new law prohibiting mailing Chinese souvenirs?