“Good things are so scarce nowadays,” says Mee-Seen Loong. Which is why nothing generates auction-room fireworks quite like when a once-in-a-lifetime work hits the block. “You cannot really place that value on the estimate, but you know that excitement is inherent in the piece,” adds Loong, a specialist in Chinese art. Rarity can feed the mythology of an object, but factoring scarcity into value is a sophisticated equation. In Episode 3, Sotheby's experts calculate the Rare Factor.