Urban Outfitters rips off indie jewelry designer
imakeshinythings.tumblr.com
imakeshinythings.tumblr.com
Even if they copied the idea, it does not appear that there is any legal recourse, as the idea is not protected by copyright. I'm not very familiar with copyright as it pertains to art, so I may make some error in separating idea from execution here.
Note that while copyright law does protect the original work, "A second work, identical to an earlier copyrighted work, does not infringe, if it is, in fact, independently created." <http://law.unh.edu/thomasfield/ipbasics/copyright-in-visual-... > Thus even if they stamp some of their pendants so as to be identical to the original works, this is not infringing, so long as the design is independently created.