LONDON.- Christie's will offer a masterpiece by Raffaello Sanzio, called Raphael (1483-1520) at the auction of Important Old Master and British Pictures on 5 July 2007 in London. One of only a handful of paintings by the artist to remain in private hands, the work portrays Lorenzo de’ Medici, Duke of Urbino and ruler of Florence from 1513 to 1519, and has not been seen in public for over 40 years. The most important Renaissance portrait to be offered at auction for a generation, and the most important work by the artist to be offered at auction in recent decades, it is expected to realize between £10,000,000-15,000,000.