Sorry I can't site a reference, but that's what pops into my head! I have a few but can't do an image for a couple of days. Pretty, aren't they?

Makes sense. The seller recently bought a large stored stash from a bead shop that closed 30-40 years ago. She has many Japanese beads. There were some of these in dark blue, but someone else pounced more quickly than I.

She had these in blue, white and green.

Actually, it was a trading post type store in Oklahoma on/near the reservation, the rez. And I messed up the date. The store closed early 70s, closer to 40 years ago. Recently, the elderly former shop keeper sold her old stock to a younger woman met through kin. Now they are being shared on the big virtual trading posts of the online world.

Here's an old scan of mine. I think the little one is also from Japan. I've since come by a couple more of those in light blue.

Ooooo, I love the autumn colors. The red bead is a fascinating variation. Thanks for sharing.

This has been my first encounter with these beads, never saw them before. How fun to find something new-to-me!