| It is known that the comma-shaped bead was manufactured approximately by the middle of the Jomon period at latest (5,000 B.C.); notably, the comma-shaped bead made of jade as well as the workshop for manufacturing the beads were discovered from 'Chojagahara Site' in Itoi-gawa River, Niigata Prefecture. |
遅くとも縄文中期（BC5,000年）頃にはヒスイ製勾玉がつくられていたことが判明しており、特に新潟県糸魚川の「長者ヶ原遺跡」からはヒスイ製勾玉とともにヒスイの工房が発見されている。 |