Mike, I have tried for almost 20 years, without success, to learn something about the background of these rectangular pieces marked as the one offered to you.
I have one in my collection very similar to the one you were offered. It is marked AUSCHWITZ. I bought it several years ago against my better judgement for $80, from a documented veteran in California. Although I was almost certain then...and still am...that it is a fake, however the old soldier swore to me by all that is "high and holy" that he took it from a drawer in a private German home in Heidelberg in the Summer of 1945, where he was being billeted.
I confirmed through independent research that the veteran was a former member of the army outfit that he told me he was in, and that they were in that area during the time frame he told me.
I have seen many examples of these pieces in all grades of quality and in various metals, and from several different KZ. If these ever in fact did exist during the period, it is my opinion that they were some type of property marker, and certainly not for identification, as all examples observed from any given camp bear the SAME number.
They are known to have been sold by WW2 Ltd in St. louis as long ago as the 1970s. I have seen them in copper, brass, and pot metal.
