## 3 Results and Interpretation  
### Stereoscopic Microscopy  
A stereoscopic microscope was used to identify the colors, distribution of bubbles, impurities, cracks, and surface weathering in the representative glass bead samples (Figure 2). All glass beads were translucent when they were blue, and opaque when they were brown and green, regardless of their excavation site.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Sample** & **Material** & **Location** & **Tomb** & **Color** & **Number** & **Internal Diameter** & **External Diameter** & **Thickness (mm)** & **Characteristics** \\ \hline S18-G-Light & & & Light blue & 2 & 0.10–0.15 & 0.35–0.42 & 0.22–0.34 & translucent, many air bells, black impurities, surface weathering \\ \hline S18-G-Brown & glass bead & No. 18 & pit tomb & Brown & 12 & 0.10–0.15 & 0.23–0.29 & 0.08–0.26 & opaque, many air bells, elongated black impurities \\ \hline S18-G-Green & & & Green & 74 & 0.10–0.15 & 0.29–0.43 & 0.19–0.32 & opaque, elongated black impurities \\ \hline \hline \end{tabular}
\end{table}
Table 1: _Cont._The blue glass beads from tomb No. 8 and the blue-green glass beads from tomb No. 11, which were excavated in fragments, had greatly weathered brown edges, and small and large cracks (Figure 2a,d). Although the edges of the brown glass beads from tomb No. 11 were not greatly weathered, there were several small cracks within the glass beads (Figure 2b).  
The green glass beads from tomb No. 11 were of a balanced round shape and did not have significant weathering (Figure 2c). The surfaces had several glass bubbles, and contained mixtures of brown, yellow, and blue substances. Unlike the glass beads from tomb No. 8, which were excavated in fragments in the same blue color, the blue-green glass beads from tomb No. 11 had small bubbles distributed in a traverse direction. This may be because the glass beads were shaped when they were not completely melted [7].  
Figure 2: Glass bead samples observed under a stereoscopic microscope and scanning electron microscope. (**a**) Blue glass from tomb No. 8. brown (**b**), green (**c**), and blue-green (**d**) glasses from tomb No. 11. (**e**) Brown glass from tomb No. 12. light-blue (**f**), brown (**g**), and green (**h**) glasses from tomb No. 18.  
Although the brown glass beads from tomb No. 12 did not have significant weathering at the edges like the brown glass beads from tomb No. 11, they contained various black particles of different sizes (Figure 2e). In addition, there was not a single brown color, but rather a mixture of light and dark brown colors. The edges of the light-blue glass beads from tomb No. 18 were weathered and brown in color, and the color was relatively uniform (Figure 2f). Bubbles of various sizes were distributed throughout the beads, as were mixtures of brown and white substances.  
The brown glass beads from tomb No. 18 showed melting traces identical to those of the brown glass beads from tombs No. 11 and 12. The surfaces of the glass also had black materials, in the form of elongated circles (Figure 2g). The surfaces of the green glass beads from tomb No. 18 had mixtures of brown, green, and light-green materials, and the edges were rounded (Figure 2h).