Upon closer inspection, it appears the design was applied to the bead in such a way that there was overlap at a "seam".

I'm not sure how this could have been done, but "transfer printing" was mentioned in Floor's thread last year in which she showed porcelain beads from Tiefenbach.

http://beadcollector.net/cgi-bin/anyboard.cgi?fvp=/openforum/&cmd=get&cG=63331313538343&zu=36333131353534&v=2&gV=0&p=

This bead is very light weight and does not seem dense enough to be fired porcelain - the weight is what initially made me think it was a plastic bead. So plaster of Paris is a possibility.