It is pretty well accepted that the pre-rizzuto knives are the first. In considering the details of some other variations, those which have square sears and semi-smooth bales are logically among the very first as well. Tang stamps and single pin also indicate a given knife is in the group of the earliest. No doubt conjecture abounds with rizzuto chronology. There is obvious difference between the pre-rizzuto and these other variations. It could be the pre-rizzuto was intended to appeal to those buyers used to Italian quality while the others were geared to be sold to tourists in Mexico which is what all rizzutos came to be. One thing is for certain. If you collect rizzutos, there is more to it than just the various lengths. To get the earliest ones, square sears, semi-smooth bales and single pin scales are must for completeness.