  Color centers in diamond micro and nano structures are under investigation
for a plethora of applications. However, obtaining high quality color centers
in small structures is challenging, and little is known about how properties
such as spin population lifetimes change during the transition from bulk to
micro and nano structures. In this manuscript, we studied various ways to
prepare diamond samples containing silicon vacancy centers and measured how
population lifetimes of orbital states change in pillars as we varied their
dimensions from approximately 1 $\mu$m to 120 nm. We also researched the
influence of the properties of the diamond substrate and the implantation and
annealing methods on the silicon vacancy inhomogeneous linewidth and orbital
lifetime. Our measurements show that nominally identical diamond samples can
display significantly distinct inhomogeneous broadening. We observed weak
indications that restricted vibrational modes in small structures may extend
population lifetimes. However, imperfections in the crystal lattice or surface
damage caused by etching reduce population lifetimes, especially in the
smallest structures.
