At face value, this is a mourning ring for Napoléon Bonaparte complete with a lock of his hair(!) under glass. On the back, it's engraved for the date of his death. Could it be? I imagine many rings were given out to loyalists, but without DNA testing the hair, we don't know for certain. At the very least, it's a nice 18k ring from the early 1800s, but it could be a historic treasure. The new owner can take the research a step further if they like.