What is the ruling on a man wearing a silver chain around his neck and a plastic bracelet on his wrist?

It is not permissible for a man to wear necklaces and bracelets, because these are adornments specific to women, and wearing them constitutes imitating women. The Messenger of Allah (peace and blessings of Allah be upon him) cursed men who imitate women. Furthermore, wearing them to ward off the evil eye or to bring good luck is a forbidden falsehood and falls under the category of polytheistic amulets.