In 1917, Pierre Cartier famously traded a double-stranded, natural pearl necklace, valued at the time for $1 million, and $100 in cash for a mansion on Fifth Avenue, where he established Cartier New York. Pearls have always exerted a powerful allure. Worn by royalty, legendary beauties and style icons – just think of Audrey Hepburn's pearl-and-diamond statement necklace in Breakfast at Tiffany's or Coco Chanel's signature layered strands, still a staple in the fashion house's runway collections today. Unlike diamonds, natural pearls emerge as finished gems, and the finest are lustrously silky and perfectly round, which makes finding a match an incredible feat. Pearls also vary in shape, size and colour, ranging from a more common cream or pink to rarer shades of black, green, blue and gold. Click ahead for an array of pearl jewels coming to auction, including pieces by legendary makers Mikimoto, Cartier and Tiffany & Co., plus one record-setting past lot.