An ancient legend which happens to be true for the universe of Lost Memories. It is a wish fulfilling blue colored jewel, that sees the deepest desires of ones mind and then telepathically asks the user if he really wants to go through with his wish.
Role in Lost Days
The Cintamani Stone doesn't play a huge role in Lost Days, as at first it isn't known that Zachary Quinn got his power from a person who once used the Stone and wished for the ability to be able to bestow psychic abilities upon others, which is how Zachary got his powers.
Role in Lost Memories
At the end of Lost Days, James announces that he finally found out, what created Zachary's powers and vows to find the Cintamani Stone and make sure, that nobody ever can use the stone again. He however then also wants to use the Stone which triggers a race between him and several rogue CIA squads who all want the Stone for themselves.