首輪
くびわ · kubiwa · JLPT N1 · noun
necklace
📿 首 (kubi) = neck + 輪 (wa) = ring: a ring worn around the neck
首 (kubi) means neck and 輪 (wa) means ring or loop. Put them together and you get a ring worn at the neck, which is a necklace or choker.
首 — hair 丷 over face 自 (eye + nose)
首 is a pictograph of a head, originally drawn with hair on top and a face below (containing the eye element 目). It meant 'head' literally, then extended to 'chief, leader, first' since the head is the topmost and foremost part of the body.