I actually tried that but unfortunately turmeric is not a reliable dye for this because its only suspended and will completely settle out of solution after a few minutes. If you try just putting turmeric in olive oil you can see this happenning fairly quickly.
In fact, most "oil soluble" dye agents are merely suspended in solution and will settle out if the oil is not viscous enough or if the dye particle size is not small enough. (however im sure that are a few that can be effectively used in this).
I notice some people release some stones that are tan inside along with the regular green colored ones and I feel that those tanned ones are indeed coming out of the gallbladder versus the fresh green ones.
Any comments are appreciated
Mike