Maybe it's black stone beads. Obsidian is a kind of black gem, which often has golden flash, so it is also called "Obsidian" and "Blackstone". Black nephrite is a kind of gem with high hardness and good gloss, which is often used in jewelry making. The combination of the color of black nephrite and the flash of gold thread makes the beads look very gorgeous and noble, so they are very popular in jewelry.