Just. for. you. Steven!
The Mirror is a magical, Gem-powered item that first appears in "Mirror Gem". Steven is given the mirror by Pearl to learn about Gem history, and he later discovers that a Gem, Lapis Lazuli, is trapped inside it. Steven sets Lapis Lazuli free by pulling her cracked gemstone out of the mirror, shattering the mirror's glass surface in the process. The remnants of the mirror are discarded afterwards.
An ornate design of silver-blue metallic material comprises the backing and handle of the mirror; Lapis' cracked gemstone was affixed to its back. The mirror itself is a round piece of reflective blue glass with a faint contour of an octagonal gemstone etched on its surface.
Pearl gives the mirror to Steven so he can learn about Gem culture and history; it can show its viewer any event it was present for since its creation. Pearl tells Steven they found the item at the Galaxy Warp. As Steven and Lapis begin communicating, she tells him she was purposely imprisoned within the mirror. Steven releases her by removing the gemstone from the back, shattering the mirror.
It is revealed that Lapis was supposed to come to Earth for only a short time but got caught in the middle of the war. She is eventually poofed by a Bismuth and a Homeworld soldier, mistaking her for a Crystal Gem, imprisoned her in the mirror. Their intention was to hold her captive and gather information about the opposing forces, which Lapis obviously couldn't give, as she was not a rebel gem. When all of the Homeworld Gems fled, she was stepped on, resulting in the damage to her gemstone, and left on Earth by the Galaxy Warp. She was eventually found by Pearl.
Lapis mentions that being on the Moon is like being in the mirror, but with an odd difference that she put herself in there.
- The eight-point star on the mirror may be a reference to the Khatim Suleiman, meaning Solomon's Ring. Islamic legends state that King Solomon captured Djinn with an eight-point star ring, similar to how Lapis was trapped inside the mirror.
- Lapis' gem was apparently damaged after she was trapped, as the crack runs across the mirror's backing.
- This is confirmed in "Same Old World" in the flashback that Lapis shows Steven. In the flashback, the mirror Lapis was trapped in was stepped on by a fleeing Homeworld Gem.
- The symbol on the front of the Mirror is similar to the flare sent out of Peridot's Escape Pod.