Manufacturing technology of ancient gold-in-glass beads from the Kazakh Altai and implications for Eurasian exchange

Gold-in-glass (GG) beads, composite ornaments encapsulating metal foil between glass layers, are widely distributed across the Mediterranean and Inner Asia, yet their presence and transmission across Inner Asia remain insufficiently understood. In particular, the mechanisms by which Mediterranean natron composite glass circulated within pastoral-nomadic steppe networks require clarification. This study examines two GG beads from a third–fourth century CE burial at Tautekeli in the Kazakh Altai, a corridor linking central and eastern steppe. Integrated SEM–EDS and micro-CT analyses demonstrate natron soda–lime glass compositions and reveal differing production strategies. Structural evidence supports a drawn-tube core with viscous outer-layer application rather than formation by double tubes. This study provides insight into the technological flexibility of GG bead production and shows that Mediterranean natron glass continued circulating across Eurasian steppe networks into the third–fourth centuries CE.