Theoretical researches, conducted during last years in Russia and abroad, founded new, hither to unknown, properties of magnetic fields, produced by constant magnets made from rare materials of Nd—Fe—B type. The paper describe the leakage fields which appeared in Kittle system of open domains. High coercitivity and definitions of the field of uniaxial anisotropy of these fields can be used for researching and separation of dia- and paramagnetic materials which include a major part of metals and alloys, and different metal salts.