Magatama in the Yayoi period, c. 300 BCE to 300 CE, are notably different from Jōmon-period magatama. 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 magatama are noted for their reverse C-shaped form, which by the end of the period became an almost squared shape. From the Yayoi period on magatama uniformly feature a bored hole that allowed the jewels to be held on a string.