[BluePill]

Yes.

[ainoko_hikaru]

I see. Thank you very much!  

[cheese (MSW)]

All e⁻ paired: diamagnetic, sample weakly repelled by magnetic field.  Sample in a Gouy or Faraday balance [google] and it will apparently lose mass when magnetic field applied.  To actually lose mass I think would violate a Law of Thermodynamics.
One or more unpaired e⁻: paramagnetic, sample is attracted into a magnetic field and will apparently gain mass.  An e⁻ has “spin” and angular momentum that causes it to have a magnetic moment.  For metal cmplxs the angular contribution is largely quenched and magnetic moments close to the spin-only values are found.  From quantum mechanics μ = √n(n+2) BM (Bohr magnetons) where n is the number of unp e⁻.
[Fe(CN)6]^4-  This is Fe(II) 3d^6 (CN^-).  As previously stated, CN^- is a strong field ligand and the d orbital splitting diagram is: t2g (↑↓)(↑↓)(↑↓)    ( )( ) eg  The ion has no unp e⁻s and is .: diamagnetic: repelled by a magnetic field.
[Fe(CN)6]^3-  This is Fe(III) 3d^5.
The d orbital splitting diagram is: t2g (↑↓)(↑↓)(↑)    ( )( ) eg  The ion has one unp e⁻ s and is .: paramagnetic, attracted into a magnetic field.  Magnetic moments are easily determined by the Gouy or Faraday (Evans) technique and it is found that the moment is ~2.3 BM (some orbital contribution) rather than 1.73 BM (√3)
F. A. Cotton, G. Wilkinson, C. A. Murillo, M. Bochmann
Advanced Inorganic Chemistry 6th ed (1999). p784, 790