Adding glass beads to your recreation persona used to be difficult. It was hard to find good matches for beads found in burial mounds, and making them required esoteric equipment and arcane skills.
Within the last ten years, the invention and proliferation of Hot Head torch heads and MAPP gas, as well as glass canes of every imaginable color has brought that to an end. Anyone can, with a small investment, learn to shape glass into marbles or beads and either make necklaces or attach them to clothes, bags or other “decorated useful artifacts.”
Glass beads have been found in a variety of colors in many cultures from the Iron Age to the present age. Some beads were traded for- the Scythians traded with the Greeks. The Vikings stole or traded from everyone. Even later historical periods like the Renaissance had lampworked glass beads. Whatever your culture is, you should be able to find some sort of appropriate beads.