|Manga Debut||Chapter 2|
Rubeus Manastone (魔石ルベウス Maseki Rubeusu) is a rare ritual item made by condensing the earth's energy. It is said to be the brightest, hardest, most colorful and most valuable mineral in the world. It is also said to increase the power of the seal if inserted on the ring. A single stone is said to be worth about 10 Billion Rel.