You might want to post this at the Marble's forum on knifeforums.com. It's my understanding that the old Marble's were 1095 and had a very good reputation indeed. The new ones are 52100, even better IMHO, and a cryogenic treatment is part of the tempering process. My Fieldcraft is one of the sharpest knives I own. (Some of the larger Marble's blades are 5160, I believe.)