  Large spatial quantum superposition of size ${\cal O}(1-10)~{\rm \mu
\text{m}}$ for mass $m \sim 10^{-17}-10^{-14}~\text{kg}$ is required to probe
the foundations of quantum mechanics and testing classical and quantum nature
of gravity via entanglement in a laboratory. In this paper, we will show that
it is possible to accelerate the two spin states of a macroscopic nano-crystal
sourced by the inhomogeneous nonlinear magnetic field in the Stern-Gerlach type
setup. We will assume that the electronic spin can be embedded at the centre of
the nano-crystal, such as the nitrogen-vacancy (NV) centre of diamond. Our
analysis will be generic to any dopant or any material. We will show that we
can create a desired superposition size within $1-2$ seconds by catapulting the
trajectories of the two spin states with a modest magnetic field gradient and
then recombine the trajectories for a coherent interference. We will show the
demanding nature of the precision required in the magnetic field to recover
$99\%$ spin coherence confidence level at the moment of interference.
