Measuring just 1.65mm, the aptly named ThinKing is a quirky watchmaking marvel inspired partly by an ultra-thin watch made 200 years earlier. Who can make the world’s thinnest mechanical watch?

The obsession with ultra-thin watches continues with the release of the Bvlgari Octo Finissimo Ultra Tourbillon (USD$678,000), which has reclaimed the title from the Piaget Altiplano Concept ...