Called Dogon, or Dutch donuts, as they originated in the Netherlands, they date back to the late 1700's and early 1800's.
Traded with the Dogon people of Mali, the annular (ring shaped) wound opalescent trade beads are hard to find nowadays, in such good condition.
The Dogon call these beads "Ashara", and were once worn only by chiefs or dignitaries in necklaces with cast bronze bells.
22" strand with about 180 beads with about a ⅜" diameter each.