Einsteinium-253 nuclei were oriented at low temperatures in a neodymium ethylsulfate lattice. From the temperature-dependent α-particle angular distribution a nuclear magnetic moment |μ|=(2.7±1.3)μN was deduced. From the values for the angular distribution function at the lowest temperatures it was possible to test the predictions of the Mang shell-model theory for the relative phases and amplitudes of the α-partial waves. As predicted, the waves of angular momentum L=0 and 2 are in phase, and the L=0 and 4 waves are out of phase. The predicted wave amplitudes are in error, especially that of the L=4 wave. The predicted relative intensities (which are proportional to the amplitudes squared) for the S, D, and G waves are 1.000:0.179:0.0052, whereas the relative intensities that best fit the experimental angular distribution are 1.000:0.216:0.0078.