In an Instagram video, social media users spotted Meta CEO Mark Zuckerberg wearing the Bulgari Octo Finissimo Ultra COSC. It's said to be world's thinnest mechanical watch, measuring1.7mm in thickness-about the width of two stacked credit cards. Priced at $5,90,000 (roughly ₹5 crore), the Octo Finissimo Ultra COSC is a limited edition with only 20 units ever to be produced.