Zirconia-based ceramics is a material with a wide variety of applications. Problems of strength of such ceramics, being prepared by different methods, under different loading conditions, and with different porosity, are of practical importance. Inhomogeneous strain distributions in different-porosity zirconia ceramics during a Brazilian test are studied using the digital image correlation and numerical simulation techniques. Spatiotemporal patterns of strain localization across the compression axis are obtained. It is found that strain components are nonuniformly distributed over the specimen surface, and zirconia experiences macroscopically localized deformation. The fracture patterns reveal the triple-cleft mode. Numerical simulations performed both for a homogeneous material and with consideration for the material inhomogeneity show that different models yield different patterns of inhomogeneous strain distribution under diametral compression. Account for internal friction and dilatancy provides eight-shaped cracks. Random distributions of strength and elastic properties over the computational domain built with the use of pseudo-random number generators and/or Gaussian random fields allow one to control the size of strain inhomogeneities.