Originating on Earth, the twelve greatest communities of magic-wielders aligned their powers to the properties of certain gemstones. Each of the Houses operated in secret from the mundane world but were in constant contact with each other. When magic started to slip way from Earth, the great Houses pooled their energies into the witch-mother Citrina who created the mystic realm of Gemworld.
For a definitive list of appearances of Houses of Gemworld in chronological order click here
COMMENTS
: The Royal Houses of Gemworld are based on birthstones as listed by the National Association of Jewelers in 1937. Aside from Citrina, and her gem citrine, there are no other specific references to the "lesser gems" of the Gemworld.