It's another one of those interesting Victorian stories
(well, at least I think they're interesting).
The centerpiece of this necklace was a pin. Consisting of a cat's eye shell in the center of a heart made from tortoise shell. The Victorians believed these shells looked like eyes and used them frequently in jewelry to symbolize the evil eye and to ward off danger and misfortune. The shell is called an Operculum, which is the door to a snail shell.
I suspect this pin was given to a sweetheart to keep her safe while her loved one was away.
Thanks so much for visiting!