An ancient Chinese legend holds that the moon has the power to create pearls, bestowing upon them its celestial glow and mystery. Yet in a market flooded with literally tons of cultured pearls, some of which sell for less than $30 a strand, rare is the pearl that possesses such supernatural charm. That’s one way to explain why this distinctive bow brooch looped with 14 carats of diamonds—suspending not one but two large baroque pearl drops, each topped by a cap of brilliant single-cut diamonds—sold for £300,000 (approximately $475,000), double the presale estimate, at the Bonhams Fine Jewellery and Iconic Gems sale in London Dec. 9. “The fact that this brooch is made up of two large natural pearls of excellent quality inevitably drove up the price,” says Jean Ghika, director of the jewelry department at Bonhams in the U.K. The other reason is, of course, the Cartier signature, circa 1960, which comes infused with a charm and mystery all its own.