All Randall miniatures (1st. and 2nd. gen.) carry a stainless blade though not all 1st. gen. are marked with the "S". The fakes are generally made from existing Randall knives like the model #2-4" or the model #10-3 so the stamp is indeed real.
In 1965 Gary Randall personally made a miniature of each Randall model as part of his knife making apprenticeship. This began what would be known as "first run" Randall miniatures. Gary's original miniatures were mounted together and are on prominent display in the new Randall Museum.
The most "common" and most popular of these early minis is the model #18. There are no production records but the consensus is between 100 and 150 mini #18's were made. There are probably less than a dozen of each of the remaining models in first run miniatures.