This is an item of stationery (paper or writing goods), or other small merchandise such as good-luck charms, mascot straps, et cetera.
Wow, what a gorgeous item! A faux-leather collar is finished with silvery-metal hardware and a string of "pearls," with a detailed silvertone cross hanging from square silvery-metal links. The cross has a creepy red "eye" in the ornament set at its center. This is a perfect cosplay accessory, and is extremely cool on its own merits, too--try it with a goth outfit!