Recently, dyed opals from Ethiopia are often seen in the market. The Ethiopian dyed opals with three kinds of common colors were studied in this paper using ordinary gemological testing methods, spectrum analysis and other methods such as absorbent experiment, soaking fading experiments and soaking dye experiments. The results show that these Ethiopian dyed opals are mainly dyed by soaking the opals in chemical pigments solutions of different colors in consideration of their relatively bigger porosity and stronger dye absorption. The surfactant containing carboxylate ions or hyperdispersant (e.g. phthalate) is often used to disperse pigments granules more evenly. The identification characteristics of Ethiopian dyed opals are as follows: ① Semitransparent to semitranslucent, dyed orange and blue samples have strong to weak play of color, whereas dyed black samples are mostly grayish blue or yellowish gray in color with strong red, yellow, green, and blue play of color, as well as strong to weak red tone and uneven dye concentration phenomenon under transmitted light. ② The absorbent of dyedopals from Ethiopia is as strong as that of the natural ones; once they absorb water, the density and weight both increase obviously, the transparence becomes stronger, and the play of color may be enhanced or weakened; the densities of dyed opals from Ethiopia vary in the range of 1.63～1.86 g/cm³, and the refractive index is 1.40, which are consistent with the data of natural ones from Ethiopia but are lower than corresponding data of opals from Australia and Mexico. ③ Observation under high-power microscope shows that the colors of the dyed opal samples are unevenly distributed: there are dye dots, dye spots, dye lumps in the inner part, more obvious dye concentration along edges, scratches and pits at the surface. ④ The solvents will change color when dyed opals are soaked in them. ⑤Roman spectrum shows that dyed opals exhibit strong fluorescent background, weak 3 362 cm^-1 peak caused by heat effect, and weak Raman scattering peak. ⑥ UV-Vis absorption spectrum indicates that dyed opals are different from natural ones.