In order for the crystal to grow properly, remove the selected crystal from the solution and separate the irregular smaller crystals again if they have merged with the basic crystal. Return the other crystals to the solution and transfer to a container suitable for heating. Add one level spoonful of bluestone powder back into the solution with the crystals and heat to near boiling while stirring. When the solution has cooled to room temperature, transfer it back to the crystallization vessel and immerse the bluestone crystal tied with thread so that it does not touch the walls of the vessel. Cover the container for crystallization with foil and let it stand overnight.