I have a modernist sterling brooch with agate that is signed STERLING flanked by two funny abstract shapes. Any idea whose mark this is? It's pretty tough to search for... http://25.media.tumblr.com/tumblr_mapjrqeki31qzx3igo2_500.jpg http://25.media.tumblr.com/tumblr_mapjrqeki31qzx3igo1_500.jpg