In the latest issue of BeadWork, August/September, Nancy Cain has instructions for a necklace she called "crystal twilight" which has rings like these as part of it. Making just these rings has set me off in new directions (bangles?) and has me experiementing with various sizes and ways of making them. She used only two sizes of silver beads, but I like the way two colors, one inside and one outside, give the ring a radiance (as in the small white one).
Basically she uses 5 rows of 8s or 11s in a flat peyote ring, with 5 rows of a smaller bead, 11s with 8s, or Delicas or 15s with 11s divided up so 2 rows are one side and three rows are on the opposite side. Then one zip stitches the sides together to make a closed circle. The only other way I knew to make such a form was to crochet a tube. These rings, being hollow are lighter weight and more pliable. I still have not gotten the right amount for a bangle. One pink circle is too small and the other one is too large. All because I refuse to count beads for my base and think I can eye the size of the circle.