They don't have religious or cultural associations in most cultures (unlike the ring finger), and, like rings on the fourth finger, they don't touch or interfere with the index/pointer finger at all.
4+ What Finger Does A Promise Ring Go On Background. Which finger—or even which hand—you wear your promise ring on is entirely up to you. Jared's® extensive online collection of promise rings range from trendy to timeless.
How To Wear A Promise Ring Quora from qph.fs.quoracdn.net
A promise ring is a promise of commitment and often precedes an engagement. What finger do you wear a promise ring on? Though the meaning of a promise ring does not change much depending on which finger it is worn, it is always better to give a little.
Left hand ring finger, just like an engagement or wedding ring.
Unlike the engagement ring, the procedure for giving this one is less rigid, and it is not so expensive. Typically they are worn on the ring finger of the left hand, in the place of an engagement ring, if the wearer is not married. Ring finger of the left hand a promise ring is a promise of commitment and often precedes an engagement. The symbol of commitment and love between you and your partner.