Celestones are obtained as rewards for quests, usually in the form of fragments or Celestones of Human, Heaven, and Earth. 20 Celestone Fragments can be converted into a Mirage Celestone, or 3 of each of the Human, Heaven and Earth Celestones. When 20 fragments sold for 10,000 , it set the price for Mirage Celestones at that price or higher. Celestones were set to zero coin in a patch in late October 2015. As of mid-2016, Mirages have begun to sell for less than 10,000.
Mirages can be made from three each of the Human, Heaven, or Earth Celestones. There was never a solid market or the other three before, but now that any price is more than they fetch at merchants, that may change.
Mirages were once able to be made from 20 fragments. The fragment reward is now as useless as medium and high level Dragon Quest items. There is money enough in this game, but the useless items are aesthetically unsettling to players to the point where they complain about the loss, and they usually prefer to complain about the money.
Mirage Celestones therefore sell at anything over 10,000 coin, up to a soft cap of about 15,000, prices becoming increasingly rare the closer they get to that.
Three Mirages is the price of a Genie. They are also used, often in great quantities, due to the low chance and randomness of it, to upgrade weapons at the Archosaur Elder.