Made in a limited run of 500, Montblanc's 'Orbis Terrarum' watch has a captivating world-time function that depicts all 24 time zones. It's designed with stacked rotating discs, the sapphire crystal one features a dimensional map of the northern hemisphere, and below that sits a guilloché-patterned one that indicates day and night. Powered by a Swiss-made calibre MB 29.20 automatic movement with a 42-hour power reserve, it's crafted from polished 18-karat rose gold and has an exhibition case…