Tiffany's smiley necklace is unmarked. Ct is fake. According to relevant information, authentic Tiffany necklaces will have brand logos, Tiffany smiley necklaces will have ct logos on pendants and chains, and sometimes designers' signatures will be added. Without these ct, they are fake. Tiffany is an American jewelry brand. 1837, the first Tiffany boutique opened in new york.