Comparison is made between PbMg 1 / 3 Nb 2 / 3 O 3 crystals grown via slow-cooling flux growth from melts composed of(flux + PbMg 1 / 3 Nb 2 / 3 O 3 ), (flux + PbO/MgNb 2 O 6 ), and (flux + oxide) components. Dielectric characterization showed no difference in the ferroelectric transition temperatures for the three different types of crystals. However, the optical transmission spectra showed significant differences between the different growth runs, as did the resulting amount of parasitic pyrochlore phase. It was found that the dearest and most regularly shaped crystals resulted from the (flux + oxide) component growth runs.