Popular in the 19th century, Lovers’ Eyes were tiny portraits painted on pieces of jewelry meant to conceal the identity of their subject. Since only an intimate acquaintance might recognize the individual’s eye, the token of affection could be proudly displayed while keeping forbidden romance a secret. Lovers’ eye jewelry pieces were sometimes studded with a diamond tear in remembrance of lost loved ones.
I recall a mystery story, I think it was by British author, Anne Perry, that featured a Lover’s eye piece of jewelry. As I recall there was a scandal tied to it, one or both of the characters was married to other people.