The gallbladder contains about the same amount of bile as the oil that is used in the flushing receipes. If you mix a clear solution (oil) with equal amounts of a colored solution (bile) you will get a colored solution. The bile inthe gallbladder will be released into the small intestines and mix with everything there..in this case the oil....so it would become green and if the stones did form in the intestines then they would be colored by the bile which is passed through the small intestines so quickly (results of Epsom Salts ) it cannot be resorbed which is the typical fate of a bile salt. A bile salt is often resorbed and excreted back into the intestines to digest a meal several times for a large meal. I have done a bunch of butchering since we raise all our own animals and I can tell you that pure bile will color anything it touches a very bright green.
As an aside I have read several posts where people have been unable to purge documented stones in their gallbladder while passing oodles of soft stones. Why would some be passed an others not? This is a confusing issue for me but I am learning a bunch from you guys and gals!