Casio Computer Co Ltd released six Adventurer’s Stone models as additions to its G-Shock series to celebrate the 40th anniversary of the G-Shock brand.
The watches are inspired by stones that adventurers have used to navigate since the Middle Ages.
Adventurers have used those stones' light-refracting properties, even on cloudy days, to determine the sun's position.
This G-Shock line was designed based on these stones' value to adventurous people.
The watches go on sale January 14 for 33,000 yen to 41,800 yen.