Questions are being raised about a 22-karat gold, jewel-encrusted crown believed to have been made in Thailand in the 15th century, and owned for the past 23 years by the Philadelphia Museum. “The crown, which resembles a cylindrical helmet, is featured on the museum’s Web site and in its collections handbook. Now, with the opening of an exhibition of Siamese art in San Francisco that includes the crown, questions have been raised in Thailand as to whether this regal object was removed from that country illegally nearly half a century ago.”