If you want to break a bead in a more-controlled manner, just place it vertically on a hard surface, and insert an awl or pointed tool into the perforation, that penetrates, but not all the way into it; and strike the tool with a hammer (once). Depending upon the material, the bead will split in two, divide in some way, or even crumble. JDA.

P.S.—the name "cement" is used for two entirely different products. One is the very hard concrete used in construction, that has many different formulas and uses (and therefore hardnesses and destructibilities). The other is usually resin-based and used as a glue.

Beads have been made from concrete materials, AND from substances (i.e. crushed glass) bound together with glue. And any of these might be characterized as "cement beads."