yes they are diamond target grips, numbered target grips as I understand occured only on the earliest M25's and M19's, well the pre model versions of those guns
As I understand it, magna grips had to be fitted more precisely to the gun since the front, bottom and back of the frame were exposed when the grips were on, so they were numbered to the gun in many cases. Target grips on the other hand only leave the back of the frame exposed so fitting was less critical and most target grips are not numbered to a specific gun.