Cross of the Church and Pontiff medal
Cross of the Church and Pontiff medal known in Latin as "Cross Pro Ecclesia et Pontifice", is the highest honor a pope can bestow upon laity and religious who have given special service to the Catholic Church.  In 1888, Pope Leo XIII instituted the medal to mark his golden jubilee anniversary (17 July, 1888, "Quod Singulari").
A physical description of the cross from NewAdvent.org,
|“||In the centre of the cross is a small medal with an image of its founder, and encircling the image are the words LEO XIII P. M. ANNO X (tenth year of his pontificate). On the obverse side are the papal emblems in the centre, and in the circle surrounding the emblems the motto PRO DEO ET PONTIFICE is stamped. On the obverse surface of the branches of the cross are comets — which with the fleurs-de-lis form the coat of arms of the Pecci family. On the reverse side are stamped the words, PRIDIE (left branch); KAL. (top branch); JANUAR. (right branch); 1888 (at the foot). The ribbon is purple, with delicate lines of white and yellow on each border. The decoration is worn on the right side of breast.||”|