The miscrostructure of graded‐index antirefection (GIAR) films was characterized using transmission and scanning electron microscopy, small‐angle X‐ray scattering, and replication. Transmission electron microscopy and X‐ray scattering results agree for the entire coarsening history of the phase‐separated substrate borosilicate glass. The complexity of the replication process and the metallization used for scanning electron microscopy caused the effective resolution limits for GIAR films to be much larger than the inherent resolution limits for each instru