I don't know where people get the idea that rosary beads are worn around the neck. When I was a small child, I saw rosary beads for the first time and thought they were a necklace -- beads on a chain, a pendant cross, they did look like that to me. But my mother set me straight.
Rosary beads are prayer beads. They are not jewelry and they are not worn as a necklace. In fact, most sets of rosary beads won't fit over most adult-sized heads and they don't have a clasp.
Every now and then I see a priest or nun in a television drama who is wearing a larger set of rosary beads around the neck in lieu of a pendant crucifix. When I see that, I can't believe the costume people came up with that or that no one on the set said anything. Monks and nuns sometimes have rosary beads worn at the waist of their habits, but you never see them worn around the neck.