There are many instances in our hobby where we have verification of a casino using a generic chip in play.
The chip should be listed in the guides as it was actually used in the gaming establishment. Since it was in play, it would be listed just as any other chip, and would be part of the collection of chips from that establishment. The difference in that type of chip would be reflected in the price guides. That chip would never attain more than a bare minimum of monetary value as the others in use might, due to it being generic and may not be one of the actual ones used there.