Chicago: A. C. McClurg & Co., 1910. Hardcover first edition - Walk's third novel, a classic vintage mystery. "A fabulous gem of unrivaled size and clarity, rumored to have been the property of Rodrigo Borgia, father of Cesare and Lucrezia... One time owner Luca Paternostro was murdered by a thief a few days after it came into his possession. A courier was lost at sea while transporting it. Now, the latest owner, Felix Page, a wealthy Chicago financier is found dead in his mansion and the Paternoster Ruby has gone missing once again." Illustrated with a full color frontispiece and 4 inserted color plates by J. V. McFall. 374 pp.