Magatama

 Magatama (勾玉, less frequently 曲玉) are curved, comma-shaped beads that appeared in prehistoric Japan from the Final Jōmon period through the Kofun period, approximately 1000 BCE to the 6th century CE.

 

promise ring

A pre-engagement ring (also known as a promise ring) is a ring given to a romantic partner to signify a commitment to a monogamous relationship, often as a precursor to an engagement ring. Promise rings can be worn on any finger, but those symbolizing pre-engagement are generally worn on the left ring finger; sometimes, the left middle finger or right ring finger is used instead to prevent confusion with an actual engagement ring. This is typically done among teenagers who are too young to be legally married, and rarely seen among adults.

Claddagh ring

The Claddagh ring (Irish: fáinne Chladaigh) is a traditional Irish ring given which represents love, loyalty, and friendship (the hands represent friendship; the heart represents love; and the crown represents loyalty).
The design and customs associated with it originated in the Irish fishing village of Claddagh, located just outside the old city walls of Galway, now part of Galway City. The ring, as currently known, was first produced in the 17th century.