Here's a photo I took at the storage facility of the British Museum, two years ago.

On the left, we see the molded Prosser beads that were the source of red glass for Nigerian powderglass beads. Next, the powderglass beads as they look after the primary firing. Then, a small group of refined beads that have been abraded and polished.

These were collected in Nigeria in ca. 1946.

Jamey