What makes this Rolex Air King so unusually valuable?

In the topsy-turvy world of watches, what typically might be considered a "Defect" is actually a boon to the value of the watch Chief among them is the fact that Rolex hardly ever makes a mistake like this-that's what makes a watch like this "Rare" in Boutros's eyes Rolex is known for an intensive quality-control process that includes several internal checks before the watch is sent out to COSC, an organisation in Switzerland that tests a watch's accuracy, after which it comes back to Rolex for a final round of looks.

"The modern Rolex is recognised for exacting quality control," says Nate Borgelt, head of sale for Sotheby's Watches in New York "This in turn makes it interesting to see small variations or errors, especially in modern-day productions from the brand, which are certainly outliers In the world of watch collectors, outliers mean rarity, and rarity can prove highly desirable" Brandon Frazin, a watch specialist at Christie's, is less sure a mistake like this instantly ups the value of this particular watch, because the Air-King isn't a very sought-after Rolex model.

Because a tropical dial makes a watch unique, it becomes a marker of collectibility. . Source