  We present the full magnetic g tensors of the $^{6}$H$_{5/2}$Z$_{1}$ and
$^{4}$G$_{5/2}$A$_{1}$ electronic states for both crystallographic sites in
Sm$^{3+}$:Y$_{2}$SiO$_{5}$, deduced through the use of Raman heterodyne
spectroscopy performed along 9 different crystallographic directions. The
maximum principle g values were determined to be 0.447 (site 1) and 0.523 (site
2) for the ground state and 2.490 (site 1) and 3.319 (site 2) for the excited
state. The determination of these g tensors provide essential spin Hamiltonian
parameters that can be utilized in future magnetic and hyperfine studies of
Sm$^{3+}$:Y$_{2}$SiO$_{5}$, with applications in quantum information storage
and communication devices.
