These portrait projecting rings were made by the Bristol artist Luke Jerram for his wife. They were inspired by the Stanhope optical jewelry of the 19th century. Luke worked with a jeweler named Tamrakar so that this ring can project the embedded image onto a wall when a light source is applied.
The image comes from a selection of miniature slides, although I think it would be really cool if they replaced the slides with an LCD screen, so you could project moving images.
While I think that it’s neat that you can use these to use these little ring projectors for wedding portraits, they should make a version with a Batman logo in it so you could use it to hail superheroes when in peril.