magatama
/ˌmaɡəˈtɑːmə/noun
A type of small, comma-shaped ornamental jewel, usually made of green jade, worn as a pendant, earring, etc., especially in Japan, where it also forms part of the imperial regalia.
Origin
Late 19th century. From Japanese magatama, lit. ‘curved jewel’ from maga-, base of magaru to curve, bend + tama ball, bead, gem, jewel.