It’s no secret that Piaget’s vintage watches are enjoying the spotlight. Stone dials, sleek dress silhouettes, funky gold shapes, and hand-etched details are again in demand, driving a niche but still a sizable portion of the secondhand market. The Swiss watchmaker has picked up on all of the vintage buzz. But to say that it’s taking its cues from the secondhand market belies the influence that the brand has long held in the realm of jewelry watches and design innovation. That Piaget chose to revisit its groundbreaking 21st Century Collection to commemorate its 150th anniversary in high jewelry and watches this year says a lot about the identity of the brand and its unique place in the watch market as it looks to a future where watches and jewelry—two adjacent but very different markets—become more intertwined with both each other and the larger fashion world. Piaget did not invent jewelry watches: The hybrid of jewelry and timepieces dates back to..