Using the unified ligand-field coupling scheme, the local structures and optical spectra of octahedral Fe3+ centers in a series of garnet crystals have been investigated systematically with two different values of parameter A(4). Our results show that the local structures of octahedral Fe3+ centers in doped systems are similar to one another if there are the same external environments around B ions in the host crystals. Being independent of the sign of the spin Hamiltonian parameter b(2)(0), it is increasingly close to zero along with structure parameter R increasing. Moreover, b(2)(0) is almost linear with the change of structure parameter theta. (C) 2009 Elsevier B.V. All rights reserved.