Stanhope

... an optical piece of jewelry. I purchased this charm in the shape of a camera from eBay. This "object of delight" contains a microphotograph of four London landmarks. It is the only stanhope I own and the fact that it is in the shape of a camera is relatively rare and particularly fitting for me given my pen-name here...

Wikipedia says: Stanhopes or Stanho-scopes are optical devices that enable the viewing of microphotographs without using a microscope