Imperial Signet Ring

The Imperial Signet Ring is an item worn only by the Emperor or Empress and the Royal Protector. During the events of Dishonored 2 it is worn by Emily Kaldwin and Corvo Attano. It is placed upon the middle finger of the left hand. Only two copies of the ring exist; one worn by the Empress, the other by the Royal Protector.

Description
The ring appears to be a double band made of silver, with a large square piece set at a 45 degree angle. Within the square is a rose and four keys, each pointing at one of the corners. Each key has a different number of teeth, ranging from one to four. The design is set upon what appears to be a navigational compass design. Upon close examination, the rose is formed by the interlocking bows of the four keys.

The keys symbolize the Empire of the Isles and are also represented on the Kaldwins' family emblem in between a pair of swans.

Although similar, Corvo and Emily's Imperial Signet Rings are not identical. Corvo's ring has a wider band without holes in, and the face is also flatter. Emily's Ring has a narrower band with two small holes in, and it has a taller face.

Function
The ring is the key of an intricate locking mechanism that seals the Imperial Safe Room off from the rest of Dunwall Tower. Designed by Anton Sokolov after the events of Dishonored, the ring's seal, when placed into a small panel next to one of the three doors to the safe room, opens and closes these doors. The ring was stolen from Corvo or Emily by Mortimer Ramsey during the Coup, and reclaiming it is necessary to be able to flee the Tower.

Trivia

 * Being part of the Kaldwin's family emblem, a similar design appears at various places: on the top part of Emily's metal throne, the blue banners hung throughout the empire, the memorial banner of Jessamine Kaldwin, and on the doors leading into the throne room.
 * According to the cosplay guide picture of Emily's outfit, the ring is made of silver.
 * A replica of the ring was available in the Collector's Edition of Dishonored 2 and from the Bethesda store.
 * The seal upon the Collector's Edition ring, and the ring in the official cosplay guide, is rotated 90 degrees anticlockwise from that in the game. This mistake is not present on the store's ring.
 * Only Emily's ring was available.
 * While some high-ranking members of the City Watch are aware of the ring and have heard rumors about its function, it is not widely recognized anywhere else, allowing Emily and Corvo to wear the ring freely.
 * In-game, the ring is classified as a mission item.
 * The achievement Imperial Seal is unlocked by recovering the ring from Ramsey during the mission A Long Day in Dunwall.