Kongoushi originally referred to Kongou-seki, i.e., diamond. However, crystal was also called Kongoushi and thus strings of beads, some of which are made of crystal, were particularly called Kongoushi-nenju. For the strand of N-289, 30 crystal beads, 44 lime tree beads and 39 dragonfly beads (a kind of glass bead) are strung on a thread and for the strand of N-290, 62 crystal beads, 8 bo tree beads and 34 dragonfly beads are used. On the main crystal beads of the two Nenju, a gilded bronze crown (J. Kan) and a ring called Marukan are attached. In the `Gohômotsu-zue' (Illustration of Imperial Treasures), a very precise drawing is shown as a string of dragonfly and crystal beads for chanting in the Buddhist services (J. Tonbodama-kongoushi-onyôju). Judging from how the beads are strung on the thread, it indicates the strand of N-289.