All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is not permissible for men to wear necklaces and bracelets, whether they are made of silver or any other material, because doing this constitutes imitation of women. The same ruling applies to wearing seashells. However, if it is worn based on a certain belief, such as seeking good fortune or warding off the evil eye, then the prohibition is more serious. It was narrated on the authority of ‘Uqbah ibn ‘Amir that the Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever wears an amulet, may Allaah not fulfill his need, and whoever wears a seashell, may Allaah not protect him." [Ahmad, Ibn Hiban and Al-Hakim]
Allaah Knows best.