I dunno about other folks...Re: Red dye and other colors
...but to me, the biggest issue here is the fact that ANY porous substance will accept dye - and no matter WHERE it came from, or where it is exposed to the dye in the human body, the fact that it was colored by the dye has no bearing whatsoever on where in the body the substance was originally located.
So whether a porous substance (ie "stone") comes from the liver, gall bladder, stomach, esophagus, mouth, small intestine, large intestine, duodenum, pancreas, or rectum (or ANY other spot in the body...if it is porous and it is exposed to dye in the intestinal tract, it WILL become the color of the dye or at least absorb part of the dye.
In NO way, does this prove or disprove where the original substance ("stone") came from at the beginning of it's journey. It only proves that the original substance ("stone") is porous and will absorb dye, and that somewhere in it's travels throughout the body, it came in contact with dye.