Yayoi period
in the Yayoi period (300 BCE-300 CE) are notably different from Jōmon-period . The jewels moved from a primitive, non-standard form towards more polished and uniform form in this period. The technology to cut large gemstones and polish jewels notably advanced in the Yayoi period. Refined materials such as jadeite, serpentinite, and glass replaced the less sophisticated materials of the Jōmon period. Yayoi period are noted for their reverse C-shaped form, which by the end of the period had become an almost squared shape. From the Yayoi period onwards, uniformly feature a bored hole that allowed the jewels to be held on a string.