"In Judaism, the wedding ring plays a major role in the Jewish wedding ceremony, but after the wedding is over, many men don't wear a wedding ring and for some Jewish women, the ring ends up on the right hand.
..Rather, the ring likely originates from the basics of Jewish law. According to Mishnah Kedushin 1:1, a woman is acquired (i.e., betrothed) in one of three ways:
Through money
Through a contract
Through sexual intercourse
Theoretically, sexual intercourse is a given after the marriage ceremony, and the contract comes in the form of the ketubah that is signed at the wedding."
https://www.learnreligions.com/the-wedding-ring-in-judaism-2076017