I noticed that all my largest "Russians" have seven sides.

So did a bit of research, and discovered some interesting things. If anyone's interested, I kept notes and pics via a PDF - message me if you want a copy.

The lower lighter blue strand was collected by Michael Heide, and I purchased it from the Picards. The decomposition of the glass seems to resemble beads found buried in jars in Diakhite, Senegal, and presumably elsewhere in West Africa. Many of the beads have iridescent patches, altho the photo doesn't show these very well.