## 1 Introduction  
Ancient glass is classified according to its composition, color, excavation sites and form, and can be subdivided into soda glass, potash glass, soda-lime glass, potash-lime glass, lead glass, and lead-barium glass on the basis of its composition. The ancient glass excavated in southern Korea belongs to the soda and potash glass categories, which can be classified into lead glass, lead-barium glass, and potash glass groups [1].  
Regarding ancient glass from southern Korea, a strong argument can be made that it was introduced from the Silk Road during movement from western Asia to China. Glassmaking techniques from Islamic civilizations spread through China to Korea and Japan [1].  
Although glass products were widely used in ancient Egypt and medieval Europe and excellent cartsmanship was developed, few glass products have been manufactured in Korea since the 10 th century. This is due to improvements in the technology involved in producing earthware and ceramics, as well as the practical use of such equipment, which have made the production of glass a low priority. Consequently, glass products are not often discovered during excavations, and they are found in a relatively small excavation area [1].  
The Suchonri tomb complex was located in the Baekje Kingdom in ancient Korea at the Suchonri archaeological site in Gongju on the southwestern Korean Peninsula (Figure 0(a),b). The tomb complex became a national designated cultural heritage site in 2005 (Historical Site No. 460). The site is estimated to have been developed from around the end of the fourth century to the early fifth century [2].  
The Suchonri tomb complex in Gongju was divided into sites 1 and 2 based on geographical features (Figure 0(c)-(e)). Site 1 consist of residential areas and graves from the 4 th to 10 th centuries, and site 2 consists of five ancient tomb areas from the 4 th to 5 th centuries (Figure 0(d),e). The glass beads used in this study were excavated from stone-linedtomb No. 8 in the first excavation site, and pit tombs Nos. 11, 12, and 18 in the second excavation site [1].  
The main component of ancient Korean glass is silica, and pulverized sand or pebbles are used as the primary materials. Generally, glass is produced by mixing fluxes and melting the mixture. Fluxes are substances, usually oxides, that are used in glasses, glazes, and ceramic bodies to lower the high melting point of the main glass constituents, usually  
Figure 1: Location map and status showing the ancient tomb complex in the Suchonri site on the Korean Peninsula. (**a,b**) Map showing the location of research area. (**c**) Location of the selected glass beads at the Suchonri site. (**d**) Primary excavation site. (**e**) Secondary excavation site.  
silica and alumina. Although it is possible to produce pure silica glass by melting silica, this was difficult with ancient techniques, as the melting temperature of silica is approximately 1850 \({}^{\circ}\)C. Therefore, ash from minerals or plants was added to lower the melting temperature to 700 to 900 \({}^{\circ}\)C [3; 4; 5; 6].  
However, as this process may result in a product with high water solubility and instability due to a low level of durability, stabilizers were sometimes added. The compositions of the stabilizers included PbO, CaO, Al\({}_{2}\)O\({}_{3}\), and MgO. In addition, materials were introduced to add color to the glass, including Ti, Mn, Fe, Cu, and Co, and it was also possible to obtain different colors by using impurities [3; 4; 5; 6].  
This study identified the physicochemical properties of glass beads excavated from stone-lined tomb No. 8 and pit tombs Nos. 11, 12, and 18 from the Suchonri tomb complex in ancient Korea using a micro-invasive technique. In addition, the color diversity and production techniques used to produce glass beads from the Suchonri site were identified based on the findings.