イヤリング vs ピアス
An イヤリング is an accessory worn on one’s ear and can be worn without piercing. This term is limited to attachments worn speficially on the ear.
A ピアス is an accessory attached via a piercing. This term can refer to an accessory worn in a piercing anywhere on the body, not limited to the ear.
Takeo runs after a mother and her child to give them a shoe they dropped. Due to Takeo’s large size and loud steps, the mother and child get frightened and run from him. After he manages to return the dropped item, Takeo returns to his friends. Rinko remarks that the scene was like “A Bear in the Forest”. Sunakawa recalls the song. Poking around the scene of a murder, Conan discovers a clue underneath a sofa. Komura sees Mie pick up an item she dropped and he wonders if it’s an earring. He fails to get a look at whether Mie’s ears are pierced. During class later, Mie shows Komura the item held up to her ear calling it a 「ピアス」. She then reveals it’s just a bead.Further Reading
Examples
A picked-up earring with イヤリング

An earring under the sofa with イヤリング

Bead as an earring with ピアス
