China has ratcheted up pressure for imperial treasures to be repatriated, condemning overseas auctions of its relics. Now Chinese art authorities are planning to catalog Chinese pieces currently housed in overseas institutions. The poster child for this movement: Two bronze animal heads looted from Beijing in 1860 by British and French soldiers, part of the Yves Saint Laurent estate auction in Paris last winter. The winning Chinese buyer refused to pay his high bid of $36 million, on patriotic grounds...