Necklace Made Of Polished Amethyst Nuggets & Puple And Wine Colored Glass Beads

I am trying to find a proper description for the technique that was used to create these lovely glass beads... It looks as if they were made by “welding” two halves together to create one bead. These streaks of purple and wine colors in the glass are amazing. The polished amethyst nuggets add the right touch to the design. I would be happy if anyone can recognize the technique of how the beads were made and tell me. Thank you in advance. P.S. The pictures were taken in the late afternoon light. The true colors are more vivid.