~~~ that can be redeemd at a casino?

If not, and you mean the total face value of all chips from all gaming jurisdiction the world over -- and from day one; it would be impossible to come to an estimate that's explainable... and, for that matter, impossible to estimate the value of chips from any one gaming jurisdiction (with only a few exceptions from areas where there was only one casino or very few casinos - and even then there would need to be backup with manufacturers' numbers). Otherwise, the guess would have to be astronomical, as the number of stars... Have another Miller Lite....