jewelyoudaoicibaDictYouDict[jewel 词源字典]
jewel: [13] Originally, jewel meant ‘costly adornment made from precious stones or metals’ – a sense now largely restricted to the collective form jewellery [14]. The main modern sense ‘gem’ emerged towards the end of the 16th century. The word comes from Anglo-Norman juel, but exactly where that came from is not known for certain. It is generally assumed to be a derivative of jeu ‘game’, which came from Latin jocus (source of English jocular, joke, etc).
=> jeopardy, jocular, joke[jewel etymology, jewel origin, 英语词源]
jewel (n.)youdaoicibaDictYouDict
late 13c., "article of value used for adornment," from Anglo-French juel, Old French jouel "ornament, jewel" (12c.), perhaps from Medieval Latin jocale, from Latin jocus "pastime, sport," in Vulgar Latin "that which causes joy" (see joke (n.)). Another theory traces it to Latin gaudium, also with a notion of "rejoice" (see joy).

Sense of "precious stone" developed early 14c. Meaning "beloved person, admired woman" is late 14c. Colloquial family jewels "testicles" is from 1920s, but jewel as "testicle" dates to late 15c.