Rare Dzi bead

After the discovery of the third gold mask, archaeologists made a priority of excavating the Chuvthag cemetery. In 2014, they uncovered five tombs there.

Tong failed to unearth more gold masks as he had hoped. But the archaeologists had another big surprise -- a rare dzi bead -- a kind of stone bead regarded by Tibetans as holding spiritual values.

To Tibetans, a dzi bead is more precious than gold masks.

"Other dzi beads have been passed down from ancient times, but this was the first discovered by archaeologists. So it's of great importance," says Zhang Jianlin, vice president of the Shaanxi Archaeological Research Institute and an expert in the field of Tibetan archaeology.

The bones of the bead's owner were too decomposed to extract DNA. But other items unearthed with it -- including a comb, a bronze mirror and bracelet -- indicated the owner was a woman of prominent status, who wore the dzi bead around her neck.

Studies by Chinese and foreign scholars show dzi beads are a type of artificially processed agate, but the source and processing technique are unknown.

The dzi bead excavated from the Chuvthag cemetery could help solve the mystery.