  The spin dynamics of the diamond NV$^{-}$ center turns out to be similar to
that of the chemical compass responsible for avian magnetoreception. We present
a simulation framework based on quantum master equation for the former that is
based upon the Radical Pair model of the latter. We show that this framework
captures all the experimentally studied behavior of the NV$^{-}$ center spin
system and can therefore be a predictive modeling tool.
