To proof that a element is diamagnetic or paramagnetic, you can hold it into a inhomogeneous magnetic field and look in wich direction the force acts. (see description [here][1]) 
I am interested into a formula, which describes the force on the matter, similar to this [one][2] ($F_z = m_z *\frac{\partial B_z(z0)}{\partial z}$). The force should not just depend on $\partial B$ but also on the matter, which is used.

Thanks in advance
  [1]: http://wwwex.physik.uni-ulm.de/lehre/gk3b-2002-2003/node33.html
  [2]: http://physics.stackexchange.com/questions/273990/force-on-matter-in-inhomogeneous-magnetic-field-diamagnetism-and-paramagnetism