首飾り
くびかざり · kubikazari · JLPT N1 · noun
necklace
首 (kubi) = neck + 飾り (kazari) = ornament, so 首飾り = neck ornament
首 means neck and 飾り means decoration or ornament. Together they name a decoration worn around the neck, which is a necklace.
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.