New Ribbon authorized for Oakleaves
By a Cabinet Order dated December 17, 1817, announcement was made that a special ribbon had been authorized for wear to indicate the second award of the Por le Mérite Order in addition to the gold Oakleaves device. The ribbon would be the same as the orginal except an additional silver metalic center stripe 8.0mm wide would be added.

referenced from The History of the Prussian Pour le Mérite Order Vol. II by William Hamelman