These are generally lampworked glass beads in iridescent metallic colours in two tones (the bead will appear to be that of two colors when checked out from distinct directions). Lampwork Lampwork beads are made by melting slender rods of glass by hand above an open up flame (typically a torch). https://spoilmevintage.co.za/2024/10/31/unlock-the-secret-to-stunning-styles-with-temus-yellow-beads-you-wont-believe-the-looks-you-can-create/