Gemstone Moon of Regol Genaralon

Located in the Regol Genaralon, the Gemstone Moon was so called because of its superb crystalline structures - each completely unique. It was not the crystalline structures however that attracted a team of scientific researchers to the moon where they erected a pre-fabricated base. Instead the base was built around a Grey Hole. The Grey Hole became very dangerous and the Doctor managed to negotiate the safe release of the scientists in exchange for the research work to be suspended. (DWAM: The Grey Hole)