Colloidal gold nanoparticles (similar to 25 nm) and Au-9(PPh3)(8)(3+) complex ions (<2 nm) are separately encapsulated in optically transparent xerogels. The high quality xerogel is found to be isotropic with no material strain or birefringence that would interfere with the magnetic circular dichroism (MCD) measurements. The MCD and absorption spectra for the surface plasmon band at 523 nm for similar to 25 nm gold nanoparticles and for the Au-9(PPh3)(8)(3+) cluster complex ion in the spectral region of 600-400 nm are examined over the temperature range from 5.5 to 295 K. The MCD spectra for the Au-9(PPh3)(8)(3+) ion (D-2h skeletal geometry) exhibit only B terms and follow the expected temperature dependent patterns for allowed electronic transitions and become better resolved at 5.5 K as compared to those at 295 K. The spectral features at 529, 448, and 402 nm have been assigned previously with the aid of a simple MO scheme to transitions to spin-orbit states of predominately triplet parentage. For colloidal gold, the observed MCD signal is large, suggesting that both the magnetic and electric in moments of the surface plasmon resonance are allowed. The MCD spectra for the surface plasmon transition at 523 nm display an A-term-like feature. To within experimental error, the MCD dispersion in the xerogel is temperature independent between 5.5 and 295 K and, thus, represents the signature of an excited-state phenomenon. It is further shown that the A-term-like dispersion of the MCD spectral feature does not originate from a single purely degenerate excited state but rather from a strong intermixing of the excited spin-orbit states.