Using theR‐line fluorescence of trace Cr3+in sintered Al2O3as an example, a method of analysis is outlined for determining the residual microstress and macrostress in a polycrystalline aggregate. It uses the shift and broadening, induced by residual stress, of a line due to a transition in an atomic system dissolved in the aggregate. For sintered Al2O3from three different manufacturers, but made for the same purpose, the isotropic and shearing components of the residual microstress and macrostress are listed in tabular form. For the isotropic component of the microstress a distribution is found, with a mean value of ∼2 kbar, in which tension and compression are equally probable.