Every great watch has a story. But some of the best stories are the ones you can't see.

Rolex etches a tiny crown into the sapphire crystal at 6 o'clock — invisible to the naked eye, only revealed at the right angle under the right light. It's been there since 2001 and most people who own a Rolex have never noticed it. Blancpain hides the initials of its founder Jehan-Jacques Blancpain on grand feu enamel dials — between the 4 and 5, or the 7 and 8 — only visible when light catches the dial obliquely. Omega built a secret Snoopy into the Speedmaster Silver Snoopy Award — invisible until you flip the watch over, run the chronograph, and watch a tiny astronaut float across the Moon on the caseback.

These are horological Easter eggs. Hidden details, secret signatures, miniature animations and invisible complications placed there by watch ...