What's always struck me as odd about these beads is the un-wearability of a whole strand of them. Rough, sharp edges, heavy...

I can see wearing one or two suspended from a leather cord or something as a pendant -
"OK, everyone from Clan A put on your stone ring and stand on this side of the dance ground" -
"I have survived the puberty ceremonies" -
"It's a lucky charm that wards off _____________"
"Cool, huh?"

Or something for ceremonial burial use, in which case the wearer wouldn't care one bit about the weight or roughness of the beads.