Abstract: A vessel for magnetically treating a fluid is generally cylindrical, having an open end and a bottom end closed by a wall; and a magnet disposed at the bottom wall of the vessel. The fluid may be a beverage in a container such as a bottle or a can which fits into the open top end of the vessel. Or, the vessel may hold the fluid. The vessel may be formed of plastic or neoprene. The magnet may be a neodymium magnet in the form of a disc. The magnet may be disposed in the vessel with its north pole facing up, may be removable so that its orientation can be changed, may be disposed on an interior or exterior surface of a bottom wall of the vessel, and may be embedded in the bottom wall. The vessel may function as a bottle holder, a cup holder, or a cup.