Numerous natural-color colored diamonds from the Aurora Butterfly of Peace and other collections were studied using a new type of fluorescence spectrometer that has many advantages for gemological research, including high portability, low cost, and rapid collection times. For comparison, 10 irradiated diamonds were also studied. With only two exceptions, the natural-color diamonds could be separated into three categories—based on the peak wavelength and shape of the fluorescence spectra—that generally corresponded to their bodycolors: (1) ~450 and ~490 nm, recorded mainly for pink, yellow, and fancy white diamonds; (2) ~525 nm, mainly for green-yellow or yellow-green and brown diamonds; and (3) ~550 nm, mainly for orange, gray-green (including chameleon), and type Ia blue-gray or gray-blue diamonds. A spectrum that is anomalous for the diamond’s bodycolor may indicate that it has been treated, and in some cases, fluorescence spectroscopy can help determine diamond type.