From The Verge:
You can now have that solar system diorama you made in school on your wrist in the form of a watch. Van Cleef & Arpel have debuted a gorgeous new astronomical watch, the 44mm Midnight Planétarium, at Geneva’s annual Salon International de la Haute Horlogerie. The watch shows both numerical time and the rotation of five planets — Mercury, Venus, Mars, Jupiter, and Saturn — visible from Earth. Each planet is represented by precious and semi-precious stones, which rotate around the sun (a stone in the center) in the amount of time it takes for the actual planet to make a rotation. You’ll easily be able to see a full rotation of Mercury every 88 days and Venus every 224 days, but it’ll take a while to see a full rotation of Saturn — 29 years to be exact.
There’s a video at the link above that shows a CGI demonstration of the watch. The real one’s probably pretty boring, action-wise.