2D multiplet:
the D means and orbital momentum of 2
the 2 means that 2s+1=2, so the spin number equals 0.5
the doublet is split in a total momentum of 1.5 and 2.5
For J=2.5, g=0.8,
for J=3.5, g=1.2
In a metal the groundstate is the lower 2D state, so g is also 0.8.