When one species colonised Agratis, they took the jewel while the creatures were hibernating, and based their entire society and advances in technology around it. When the Jewel became a museum exhibit, the Fourth Doctor said it was spoken of as "the most beautiful gem in all of creation" and that some said "you [could] see infinite complexity in the facets of the Jewel".
Roget, discovering its true purpose, returned the Jewel, reawakening the creatures. The Doctor realised that the colonists had to find a way to live with the crystalline creatures and no longer relied on the Jewel as a source of income if they wished to stay on Agratis. (COMIC: A Rare Gem)