I think it's for decoration. It was first produced in Egypt and later became an important handicraft in Greece and Rome. There are many such glass products in Rome's foreign trade, which are all over the commercial center of the Silk Road. China also unearthed the so-called "colored glaze", whose professional name is "tire-stirring glass". In addition to cups, bottles, bowls, plates and other utensils, a large part of them are such decorative beads, which, according to research, are "Daqin beads" in ancient poetry. For example, Xin Yannian's Lin Yulang: lantian jade is in the head and Zhu Qin is in the ear.