Good Evening Martin thanks for writing in and attaching a photo. I haven't ever seen a compass ring before - either an enterprising maker or a historically commemorative ring - commemorating the modern compass.
At the turn of the century innovative jewelers looking for unconventional alternatives to the age-old circle the finger with a ring, came up with all different designs, such as ring as watch, ring as container for lethal pill, ring that could be used as a camera to spy which is evocative of the Cold War between the USSR and the West that followed World War II - these rings are called Novelty Rings.
