I agree with Joyce. These beads have a black core with twisted black/white stringer glass wound around the core. The white spots are where the white part of the twisted stringer is under the black stringer, but on top of the core glass.

Molten glass is pulled off the lump into 'strings'. One white string and one black string are twisted together and the resulting spiral rope/string is used to decorate. It's a standard lampwork technique.