Turns out that pictures are worth way more than a thousand words. At a Christie's auction in London, a rare chalk drawing of a woman's head by Raphael—a figure that shows up in the background of his seminal 1511 Vatican-library fresco "Parnassus"—sold for $48 million, the most paid for a work of art all year. The Raphael painting, which sold for double its high estimate, eclipsed the auction's expected star, a 1658 portrait of a man in a sash by Rembrandt van Rijn that hadn't been publicly seen for 40 years, which sold for $33.2 million, well over its low estimate of $28 million. The sales signal that art buyers are willing to shell out for old masterpieces even though the market for living artists remains shaky. On Wednesday, rival Sotheby's will auction a portrait by Sir Peter Paul Rubens dating to around 1603, and that is expected to fetch at least $6.5 million.