John, on diamonds, see this: http://mises.org/econsense/ch91.asp
And this: http://mises.org/daily/4967/
On the origins of antitrust: http://www.cato.org/pubs/journal/cj9n3/cj9n3-13.pdf
On barriers to entry, what barriers? If those barriers are imposed by government, then that’s your problem. If you just mean it costs a lot to start an auto plant, that’s something different. George Reisman deals with this in this article: http://mises.org/freemarket_detail.aspx?control=384
