Ok, I took some quick pics. According to a book I have, this would be celuloid. But I have always thought celluloid was light and delicate. this necklace the chunky sound of bakelite, resembles a bakelite smell, although it smells a little fishy, if that makes any sense. I know, I know, ew. but after doing more research, I am wondering if this is isn't French Bakelite. According a website I found, french bakelite is supposed to resemble bone or ivory. Look at the close up of the bead.
<img src="http://members.sparedollar.com/debutanteclothing/bakelite-necklace.jpg">
<img src="http://members.sparedollar.com/debutanteclothing/bakelite-necklace-detail.jpg">
<img src="http://members.sparedollar.com/debutanteclothing/bakelite-necklace-screw-cla.jpg">