This is such an interesting ring. It appears that it may well have been someone's wedding posie, because the inscription inside reads "Time Shall Tell I Love Thee Well." Then, unfortunately a young man, most likely the woman's husband, died tragically in the Battle of Havana in 1762. This was a battle that was part of the Anglo-Spanish War. Apparently, she then took her wedding ring, and had it adjusted to a memorial ring. That scenario makes sense except that the enamel on the top of the ring is white, and that usually denotes virginity. Maybe they did not get a chance to get married?? Guess we will never know for sure, but the outside of the ring, contains white enamel and the words in gold are "JA Walker, Killed at the Hava 1762 AET 32. The ring is a size 6 to 6 and 1/4, and it can not be resized. What a fascinating piece of history. Of course I want to keep this one, but their are several I want to keep, and unfortunately, I must let some go. NOTE: A fellow dealer has sent me this information regarding this ring and the person for whom it immortalized.
I have just researched it to a Lieutenant James Walker (commander of a British Royal Navy Cutter called "Lurcher"), according to an official report, James was killed on the 13th May 1762, whist exploring Chorea river on "mere curiosity" official description of death - but likely following secret orders. Cutters were used for reconnaissance missions, similar to Captain and Commander
The ring looks much earlier, I would say late 17th century. It more likely belonged to the mother or sister who inherited it, having her brother as a memorial. I do like your idea of a betrothal ring, but unless the makers mark ties in with the 1740's it must have been an antique sentimental piece to begin with.